ANTHONY      .  .N3ROC.:      ..     . 


UNIVERSITY  OF  CALIFORNIA 

MEDICAL  CENTER  LIBRARY 

SAN  FRANCISCO 


Gift  of 
J.J.  McGinnis,  M.D. 


TEXT-BOOK 

OF 


CHEMISTEY 

INORGANIC  AND  ORGANIC 
WITH  TOXICOLOGY 


FOR  STUDENTS  OF  MEDICINE,  PHARMACY, 
DENTISTRY  AND  BIOLOGY 


BY 

R.  A.  WITTHAUS,  A.M.,  M.D. 

LATE    PROFESSOR    OF    CHEMISTRY,    PHYSICS    AND    TOXICOLOGY    IN     CORNELL    UNIVERSITY 


,  i&ebteeb  Cbttion 

BY 

R.  J.  E.  SCOTT,  M.A.,  B.C.L.,  M.D. 

FELLOW    OF    THE    NEW    YORK    ACADEMY    OF    MEDICINE:    EDITOR    OF    "  WITTHAUS'    ESSENTIALS 
OF    CHEMISTRY    AND    TOXICOLOGY,"    ETC.,    ETC. 


NEW  YORK 

WILLIAM  WOOD  AND  COMPANY 

MDCCCCXIX 


COPYRIGHT,  1919 
BY  WILLIAM   WOOD  AND  COMPANY 


w 


PREFACE 

In  the  preface  to  the  earlier  editions  of  this  book  the  author  clearly 
specified  its  scope  and  purpose.  The  general  plan  of  the  work  remains 
unaltered,  and  may  be  indicated  by  the  following  extracts  from  the 
preface  to  the  sixth  edition. 

'  The  main  purpose  of  the  section  on  inorganic  chemistry  is  to 
supply  certain  data  which  shall  serve  as  the  text  upon  which  to  discuss 
the  general  principles  of  chemistry.  It  is  the  opinion  of  the  author 
that  the  object  of  chemical  teaching  should  not  be  to  lay  up  in  the 
memory  of  the  student  a  store  of  isolated  facts,  but  rather  to  train  his 
mind  in  those  general  principles  by  which  he  may  reason  out  chemical 
problems  for  himself.  If  a  teacher  of  chemistry  to  medical  students 
aim  merely  to  supply  them  with  chemical  facts,  he  and  they  are  fore- 
ordained to  disappointment,  but  if  the  student  be  led  to  '  think  in 
chemistry,'  the  success  and  possible  extent  of  the  teaching,  both  in 
the  fundamentals  and  in  the  superstructure  of  organic  and  physio- 
logical chemistry,  which  can  be  attained,  will  be  surprising  and 
delightful  to  both  instructor  and  pupil.  And  in  this  connection  it 
must  be  said  that  the  order  of  consideration  of  the  several  subjects 
which  has  been  here  followed,  because  it  is  logical,  is  not  recommended 
in  the  teaching  of  students.  The  study  should  begin  with  that  of  a 
few  elements  and  compounds,  the  consideration  of  the  general  physical 
and  chemical  principles  being  taken  up  as  material  for  their  discussion 
is  supplied. 

1 '  The  section  on  organic  chemistry  has  been  rearranged  in  the  light 
of  further  information  upon  the  relationship  of  substances,  and 
somewhat  extended,  the  prominence  given  to  this  branch  of  the  subject 
the  author  believes  to  be  justified,  notwithstanding  its  intricacy  and 
the  impossibility  of  teaching  it  satisfactorily  to  those  not  well  grounded 
in  general  chemistry,  because  of  the  intimate  connection  of  organic 
chemistry  with  physiology  and  with  modern  pharmacy,  and  the 
impossibility  of  the  comprehension  of  the  problems  of  animal  and 
pharmaceutical  chemistry  without  the  possession  of  an  adequate 
knowledge  of  the  principles  of  organic  chemistry/' 

Since  the  first  edition  of  this  book  appeared,  and  particularly  since 
the  death  of  its  distinguished  author,  many  changes  have  occurred 
in  the  medical  curriculum;  and  not  the  least  of  these  pertain  to  the 

iii 


92790 


IV  PREFACE 

subject  of  chemistry.  Inorganic  chemistry  and  the  principles  of 
organic  chemistry  are  now  generally  presumed  to  have  been  mastered 
in  the  preparatory  schools,  and  their  study  is  reviewed  and  amplified 
in  the  first  year  of  the  medical  course  as  preliminary  to  the  important 
(special)  subject  of  physiological  chemistry. 

The  book  is  still  intended  mainly  for  medical  students,  and  the 
present  revision  has  been  made  with  the  purpose  of  providing  a  work 
which  shall  be  suitable  for  students  in  the  preparatory  and  scientific 
schools,  and  which  may  also  serve  as  a  text-book  for  the  medical  or 
professional  student  throughout  his  college  course. 

During  the  process  of  revision  the  main  difficulty  has  been  to  pre- 
vent the  book  from  becoming  of  unreasonable  size.  Many  of  the 
sections  on  Physics  have  been  omitted,  it  being  presumed  that  the 
student  possesses,  and  has  studied,  a  text-book  on  that  subject.  The 
part  dealing  with  Physiological  Chemistry  is  omitted,  because  the 
subject  is  now  of  such  importance  and  of  such  dimensions  that  its 
study  is  more  advantageously  made  from  special  text-books,  of  which 
there  are  now  many  excellent  ones  available.  Such  of  the  organic 
chemistry  as  could  be  spared  has  also  been  left  out,  and  further  space 
has  been  gained  by  printing  in  smaller  type  the  sections  on  toxicology 
and  some  of  the  less  important  general  topics.  The  equations  have 
been  printed  each  on  a  line  by  itself,  so  as  to  make  the  subject  clearer 
and  more  attractive  to  the  beginner.  Care  has  been  taken  not  to 
make  the  book  (particularly  the  part  dealing  with  Organic  chemistry) 
a  mere  catalogue  of  names  and  formulae. 

New  material  has  been  added  where  it  was  considered  necessary,  and 
care  has  been  taken  to  present  and  emphasize  general  principles  rather 
than  isolated  facts.  In  several  of  the  sections  of  the  organic  chemistry 
equations  showing  the  Grignard  reactions  have  been  freely  introduced. 
Many  of  the  new  paragraphs  were  indicated  by  the  late  Professor 
Witthaus  as  desirable,  and,  in  some  cases  they  have  been  taken  from 
his  manuscript  notes. 

R.  J.  E.  SCOTT. 
New  York. 

September,  1918. 


TABLE  OF  CONTENTS 

INTRODUCTORY—  GENERAL  CHEMISTRY 

PAGE 

Matter  —  Force  —  Chemistry  ..........................         1 

General  Properties  of  Matter: 

Indestructibility  —  Impenetrability  —  Divisibility  —  Inertia 
—Weight  —  Apparent  Weight  —  Energy  —  Specific 
Weight  —  Density  —  Pressures  —  States  of  Matter  — 
Cohesion  .......................................  2 

Special  Properties  of  Solids,  Liquids  and  Gases  .............         4 

Crystallization  —  Allotropy  —  Diffusion  —  Boyle-Mariotte 

Law  —  Absorption  of  Gases  .......................       4 


Some  Physical  Actions  of  Chemical  Interest  ...............       11 

HEAT: 

Temperature  —  Thermometers  —  Thermal    Unit  — 
Changes  in  Volume  —  Dalton-GayLussac  Law  — 
Law  of  Charles  —  Absolute  Temperature  —  Change 
of    State—  Fusion  —  Latent    Heat—  Solution  - 
Congelation  —  Vaporization  —  Gases   and  Vapors 
—Boiling  —  Liquefaction  —  Distillation  —  Subli- 
mation —  Specific  Heat  ......................       11 

ELECTRICITY  : 

Insulators  —  Conductors  —  Ions  —  Galvanic  Electricity 
—  Electromotive  Force  —  Resistance  —  Ohm's  Law 
—Electrolysis  —  Electrical  Units  ...........  ...  17 

Chemical  Phenomena  ....................................       21 

Elements  —  Compounds  —  Mixtures  —  Laws  Governing  the 
Combination  of  Elements  —  Molecular  and  Atomic 
Theories  —  Atomic  Weight  —  Molecular  Weight  —  Mol 
—Molecular  Volume  —  Valence  —  Symbols,  Formulae 
and  Equations  —  Electrolysis  —  Acids,  Bases  and  Salts 
—  Concentration  —  Stoichiometry  —  Nomenclature  — 
Radicals  —  Composition  and  Constitution  —  Chemical 
Energy—  Chemical  Equilibrium  —  Reversible  Re- 
actions —  Mass  Action  —  Chemical  Effects  of  Light  — 
Classification  of  Elements  —  Periodic  Law  ..........  21 


VI  TABLE   OF   CONTENTS 

INORGANIC  CHEMISTRY 

PAGE 

Typical  Elements    57 

Hydrogen   57 

Oxygen — Ozone   59 

Compounds   of   Hydrogen   and   Oxygen:      Water— 

— Natural  Waters — Hydrogen  Dioxide 62 

Elements  which  form  no  Compounds  72 

Helium — Neon — Argon — Krypton — Xenon — Niton   72 

Acidulous  Elements   73 

CHLORINE  GROUP 73 

Fluorine  and  its  Compounds  73 

Chlorine  and  its  Compounds 74 

Bromine  and  its  Compounds 80 

Iodine  and  its  Compounds  81 

SULPHUR  GROUP  83 

Sulphur  and  its  Compounds 84 

Selenium  and  Tellurium  93 

NITROGEN  GROUP 93 

Nitrogen  and  its  Compounds — Atmospheric  Air  ....  94 

Phosphorus  and  its  Compounds  103 

Arsenic  and  its  Compounds 110 

Antimony  and  its  Compounds 120 

BORON  GROUP 123 

Boron  and  its  Compounds 123 

CARBON  GROUP 124 

Carbon  124 

Silicon  and  its  Compounds 127 

VANADIUM  GROUP 128 

Vanadium — Columbium — Tantalum  128 

MOLYBDENUM  GROUP 128 

Molybdenum — Tungsten — Osmium 128 

Amphoteric   Elements    129 

GOLD  GROUP 129 

Gold  and  its  Compounds 129 

IRON  GROUP 130 

Chromium  and  its  Compounds 130 

Manganese  and  its  Compounds 131 

Iron  and  its  Compounds 132 


TABLE   OF   CONTENTS  Vll 

PAGE 

URANIUM  GROUP  137 

Uranium  and  its  Compounds 137 

LEAD  GROUP 138 

Lead  and  its  Compounds 138 

BISMUTH  GROUP  142 

Bismuth  and  its  Compounds 142 

TIN  GROUP 144 

Titanium 145 

Zirconium  145 

Tin  and  its  Compounds 145 

PLATINUM  GROUP  147 

Palladium — Platinum  and  its  Compounds  147 

RHODIUM  GROUP  147 

Rhodium — Ruthenium — Iridium 147 

Basylous  Elements 149 

SODIUM  GROUP 149 

Lithium  and  its  Compounds 149 

Sodium  and  its  Compounds  151 

Potassium  and  its  Compounds 156 

Caesium — Rubidium  163 

Silver  and  its  Compounds 164 

Ammonium  Compounds  165 

THALLIUM  GROUP  168 

Thallium  168 

CALCIUM  GROUP  168 

Calcium  and  its  Compounds 168 

Strontium  and  its  Compounds 171 

Barium  and  its  Compounds 171 

MAGNESIUM  GROUP 172 

Magnesium  and  its  Compounds 173 

Zinc  and  its  Compounds 175 

Cadmium 177 

ALUMINIUM  GROUP 177 

Glucinum — Scandium — Gallium — Indium  177 

Aluminium  and  its  Compounds 178 

NICKEL  GROUP t 180 

Nickel  and  its  Compounds 180 

Cobalt  181 

COPPER  GROUP  181 

Copper  and  its  Compounds 181 

Mercury  and  its  Compounds  184 


Vlll  TABLE   OF   CONTENTS 


ORGANIC  CHEMISTRY 

PAGE 

Compounds  of  Carbon: 

Organic  Chemistry — Homologous  Series — Isomerism — 
Elementary  Organic  Analysis — Determination  of  Mo- 
lecular Weights — Determination  of  Constitution — 
Characterizing  Groups — Nomenclature  —  Classifica- 
tion of  Carbon  Compounds 191 


Open  Chain,  Aliphatic,  Acyclic,  or  Fatty  Compounds 201 

Hydrocarbons   201 

Saturated  Compounds — Methane  Series   201 

Hydrocarbons   202 

Haloid  Derivatives   204 

.Oxidation  Products  208 

Alcohols   210 

Aldehydes  and  Ketones 225 

Carbohydrates    235 

Carboxylic  Acids    250 

Alcohol-acids — Oxyacids    259 

Aldehyde-acids   265 

Ketone-acids  266 

Oxyaldehyde  and  Oxyketone  Acids 266 

Simple   ethers    267 

Acid  Anhydrides    269 

Acidyl  Halides 270 

Oxides  of  Carbon  270 

Esters — Compound  Ethers   275 

Sulphur  Derivatives  of  the  Paraffins  284 

Organo-metallic  Compounds 288 

Nitrogen  Derivatives  of  the  Paraffins 291 

Nitroparaffins    292 

Amines  and  Ammonium  Derivatives   292 

Oxyamines — Hydramines — Diamines 296 

Amidines — Amid  ximes — Hydroxamic  Acids  .. .  300 

Guanidine  and  its  Derivatives 301 

Hydrazines — Hydrazides  302 

Nitriles — Cyanogen  Compounds 303 

Amides  310 

Thiourea  and  Thiocarbamic  Acids 316 

Compound  Ureas  316 


TABLE   OF   CONTENTS  ix 

PAGE 

Nitrogen    Derivatives    of    Alcohols,    Aldehydes 

and  Ketones  319 

Nitrogen  Derivatives  of  Acids 321 

Phosphorus,  Antimony  and  Arsenic  Derivatives 326 

Unsaturated  Aliphatic  Compounds 327 

Hydrocarbons   327 

Oxidation  Products 330 

Sulphur  and  Nitrogen  Compounds 333 

Closed  Chain,  Aromatic,  or  Cyclic  Compounds 334 

Carbocyclic  Compounds 335 

Hexacarbocyclic  Compounds — Aromatic  Substances 336 

Monobenzenic  Compounds 341 

Hydrocarbons 341 

Haloid  Derivatives 343 

Phenols 344 

Quinones    350 

Aromatic  alcohols  351 

Alphenols 352 

Aldehydes  353 

Ketones   354 

Aromatic  Carboxylic  Acids   355 

Phenol  Carboxylic  Acids  and  their  Esters 357 

Phenylic  Ethers— Glucosides    360 

Anhydrides  and  Acid  Halides 364 

Aromatic  Sulphur  Derivatives — Sulphonic  Acids  365 

Nitrogen-containing  Derivatives  of  Benzene 367 

Hydroaromatic  Compounds  with  a  Single  Nucleus. .  381 

Hydrocarbons   381 

Hydroaromatic   alcohols    382 

Hydroaromatic  Ketones  and  Acids 383 

Compounds  with  Condensed  Nuclei 385 

Condensed  Hydrocarbons    386 

Phenols — Quinones    386 

Diphenyl  and  its  Derivatives 388 

Diphenyl     Paraffins — Diphenyl     Olefines — Diphenyl 

Acetylenes   388 

Phenols— Alcohols 389 

Heterocyclic  Compounds 389 

Mononucleate  Heterocyclic  Compounds  391 

Five-membered  rings   391 

Six-membered  rings   396 


X  TABLE   OF   CONTENTS 

PAGE 

Condensed  Heterocyclic  Compounds 414 

Condensed  Nuclei  Containing  a  Nitrogen  Member  415 

Alkaloids   419 

Ptomaines,  Leucomain^s  and  Toxines 442 

APPENDIX 445 

INDEX  .  449 


TABLE  OF  WEIGHTS  AND  MEASURES 


WEIGHTS 

milligram  =  0.001  gram  = 


0.015  grain  Troy. 
0.154      " 
1.513  grains    " 
15.432     " 


1  centigram  =  0.01 

1  decigram    =  0.1 

i  GRAM 

1  decagram   =      10  grams  =154.324     "         " 

1  hectogram  =    100     "       —     0.268  pound    " 

1  kilogram     =1000     "       =     2.679  pounds " 

1  grain    =      0.065  gram. 

1  dram    =      3.888  grams. 

1  ounce  =    31.103      " 

1  pound  =  373.25 

1  pound  Avoirdupois  =  453.5925  grams. 
1  kilo  =•     2.2046  pounds  Avoirdupois. 

MEASURES  OF  LENGTH 
1  millimeter  =0.301  meter  = 


1  centimeter  =  0.01 

1  decimeter    =01 

i  METER 

1  decameter 

1  hectometer  =    100 

1  kilometer     =  1000 


0.0394  inch. 
0.3937    ll 
3.9371  inches. 
=    39.3708      " 

=      10  meters  =    32.8089  feet. 
=  328.089    " 
=     0.6214  mile. 


1  inch  =    2.54  centimeters. 
1  foot  =  30.48  centimeters. 

MEASURES  OF  CAPACITY 


1  milliliter 
1  centiliter 
1  deciliter 
i  LITER 
1  decaliter 
1  hectoliter 
1  kiloliter 

=       1 

=      10 
=    100 
=  1000 

c.c.  =  0.001  liter 
"    =0.01      " 
=  0.1 

=      10  liters 
=    100    " 
=  1000    " 

0.0021  U.  S.  pint. 
0.0211      " 
0.2113     " 
1.0567      "     quart. 
2.6418     "      gallons. 
26.418       " 


=  264.18 

MEASURES  OF  VOLUME 

cubic  meter          =  1000  liters. 


cubic  centimeter  = 
liter  = 

liter  = 

1  minim  = 

1  fluid  dram 

1  cubic  centimeter  = 

1  fluid  ounce 


0.001  liter. 

1  cubic  decimeter. 

1.0567  quarts. 

0.0614  cubic  centimeter. 

3.70  cubic  centimeters. 

0.061  cubic  inch. 

29.57  cubic  centimeters. 

47§.ll  cubic  centimeters, 
xi 


SIGNS  AND  ABBREVIATIONS 


The  figures  in  parentheses  indicate  the   page  upon   which  the  meaning  of 
the  sign  or  abbreviation  is  described. 


[a] 


^Specific  rotary  power  for  so- 
dium light. 

= Water  of  crystallization  (64). 

^Atmospheric  pressure. 

^Boiling  point  (16). 

= Asymmetric  carbon  atom  ( 239 ) . 

= Asymmetric  carbon  atom  (239 ) . 

=Gram  calorie    (12). 

=Cubic  centimeter. 

—Cubic  centimeter. 

—Centimeter. 

^Chemically  pure. 

=Dextrogyrous  (239). 

^dilute. 

=Racemic    (239). 

=Decimeter. 

= Electromotive  force  (20). 
EMF  ^Electromotive  force  (20). 
Eq-N  ^Equivalent  normal  solution 

(38). 

f.p.      ^Fusing  point   (14). 
gm      ^:Gram. 
i          =Racemic   (239). 
i          =Iso. 
insol.  ^Insoluble. 
K        ^Rational  calorie  (12). 
kg       ^Kilogram. 
kg:cal=Large  calorie  (12). 
L         =Liter. 
i          =Laevogyrous  (239). 


aq 

atm 

b.p. 

C 

C* 

cal. 

cc 

c.c. 

cm 

C.P. 

d 

dil. 

d+1 

dm 

E 


m 

m 

mm 

M-N 

M.w. 

N 

N/10 

n          = 

o          = 

p 

ppt. 

pts. 

R 

R 

r 

sp.  gr. 

SS 

T 

t 

U.S.P. 
Vm 

Vs 
A 


Meter. 
Meta. 

Millimeter. 

Molecular  normal  solution  (  37  ) 
Molecular  weight. 
Normal  (38). 
Tenth  normal   (38). 
Index    of    refraction    for    so- 
dium light. 


:Para. 

Precipitate. 

Parts. 

A  cyclic  compound. 

Resistance. 

Racemic  (239). 

Specific  gravity. 

Standard  solution   (38). 

Absolute  temperature   (13). 

Temperature  in  degrees  Centi- 

grade. 

United  States  Pharmacopoeia. 
Molecular  volume  (29). 
:Specific  volume   (4). 
Double  linkage. 
Wave  length  of  light. 
Micromillimeter=.001      milli- 

meter. 

Dextrogyrous. 
Laevogyrous. 


xii 


TEXT-BOOK  OF  CHEMISTRY 


INTRODUCTORY— GENERAL  CHEMISTRY. 

Matter  and  Force. — As  we  only  become  cognizant  of  matter  by 
the  action  of  force  upon  it,  or  of  force  through  its  effects  upon  mat- 
ter, our  appreciations  of  each  are  so  interwoven  that  each  is  usually 
defined  in  terms  of  the  other.  This  "argument  in  a  circle"  may  be 
avoided  by  saying  that  matter  is  that  which  occupies  space. 

In  popular  language  the'  words  matter  and  substance  are  used 
synonymously;  but  in  chemical  language  the  latter  word  has  a  more 
narrow  meaning.  A  substance  is  a  species  of  matter,  having  con- 
stant characters  and  properties  by  which  it  may  be  recognized,  and 
differentiated  from  other  substance  species,  irrespective  of  its  shape. 
Thus  sulphur,  water,  chalk  are  chemical  substances,  each  of  which, 
in  any  form  in  which  it  may  appear,  has  definite  qualities  by  which  it 
may  be  distinguished  from  all  other  species  of  substance. 

Force  is  that  which  produces,  or  tends  to  produce  motion,  or 
change  of  motion  of  matter. 

Chemistry. — The  simplest  definition  of  chemistry  is  a  modifica- 
tion of  that  given  by  Webster :  That  branch  of  science  which  treats 
of  the  composition  of  substances,  their  changes  in  composition, 
and  the  laws  governing  such  changes. 

A  bar  of  soft  iron  may  be  made  to  emit  light  when  heated,  or 
sound  when  caused  to  vibrate,  or  magnetism  when  under  the  influ- 
ence of  an  electric  current.  Under  the  influence  of  these  physical 
forces  the  iron  suffers  no  change  in  composition,  and,  on  cessation 
of  the  action  of  the  inciting  force  the  iron  returns  to  its  original 
condition.  But  if  the  iron  is  heated  in  an  atmosphere  of  oxygen, 
both  the  iron  and  a  part  of  the  oxygen  disappear,  and  a  new  sub- 
stance, a  new  chemical  species,  is  produced,  having  properties  of  its 
own,  different  from  those  of  either  the  iron  or  the  oxygen.  In  this 
case  there  has  been  chemical  action,  causing  change  of  composition, 
as  the  new  substance  contains  both  iron  and  oxygen.  The  result  of 
such  action  is,  moreover,  permanent,  and  the  new  product  continues 
to  exist,  until  modified  by  some  new  manifestation  of  chemical  action. 

While  chemical  action  is  thus  different  in  its  results  from  the 
action  of  physical  forces,  there  exists  the  most  intimate  relation 
between  them.  The  line  of  demarcation  between  chemical  actions 
and  certain  physical  actions,  such  as  solution,  although  distinct,  is 
narrow.  Many  chemical  actions  take  place  only  under  certain  physi- 

1 


2  TEXT-BOOK   OF   CHEMISTRY 

cal  conditions,  such  as  of  temperature;  or  are  provoked  by  physical 
forces,  such  as  light. 

It  is  assumed  that  the  student  has  already  acquired  a  grounding 
in  physics,  and  that  he  is  in  possession  of,  and  uses,  a  standard  text- 
book on  that  subject. 

GENERAL  PROPERTIES  OF  MATTER. 

Indestructibility. — The  result  of  chemical  action  is  change  in  the 
composition  of  the  substance  acted  upon,  a  change  accompanied  by 
corresponding  alterations  in  its  properties.  Although  we  may  cause 
matter  to  assume  a  variety  of  different  forms,  and  render  it,  for  the 
time  being,  invisible,  yet  in  none  of  these  changes  is  there  the  smallest 
particle  of  matter  destroyed.  When  carbon  is  burned  in  an  atmos- 
phere of  oxygen,  it  disappears,  and,  so  far  as  we  can  learn  by  the 
senses  of  sight  or  touch,  is  lost;  but  the  result  of  the  burning  is  an 
invisible  gas,  whose  weight  is  equal  to  that  of  the  carbon  which  has 
disappeared,  plus  the  weight  of  the  oxygen  required  to  burn  it. 

Impenetrability. — Although  one  mass  of  matter  may  penetrate 
another,  as  when  a  nail  is  driven  into  wood,  or  when  salt  is  dissolved 
in  water,  the  ultimate  particles  of  which  matter  is  composed  cannot 
penetrate  each  other,  and,  in  cases  like  those  above  cited,  the  particles 
of  the  softer  substance  are  forced  aside,  or  the  particles  of  one 
substance  occupy  spaces  between  the  particles  of  the  other.  Such 
spaces  exist  between  the  ultimate  particles  of  even  the  densest  sub- 
stances. 

Divisibility. — All  substances  are  capable  of  being  separated  by 
mechanical  means  into  minute  particles.  Although  we  have  no  direct 
experimental  evidence  of  a  limit  to  this  divisibility,  we  are  warranted 
in  believing  that  matter  is  not  infinitely  divisible.  A  strong  argu- 
ment in  favor  of  this  view  is  that,  after  physical  subdivision  has 
reached  the  limit  of  its  power  with  compound  substances,  these  may 
be  further  subdivided  into  smaller,  dissimilar  quantities  by  chemical 
means.  The  limit  of  physical  subdivision  of  matter  is  the  molecule 
of  the  physicist,  the  smallest  quantity  of  matter  with  which  he 
has  to  deal,  the  smallest  quantity  that  is  capable  of  free  existence 
(pp.24,  25). 

Inertia — is  that  negative  quality  of  matter  by  virtue  of  which  it 
cannot  of  itself  produce  any  change  in  the  condition  of  rest  or  of 
motion  in  which  it  may  be.  If  matter  be  at  rest  it  can  only  be  put  in 
motion  by  the  expenditure  of  work  upon  it,  and,  if  it  be  in  motion, 
such  motion  will  continue,  rectilinear,  uniform,  and  indefinite,  unless 
interfered  with  by  the  interposition  of  other  energy. 

Weight. — All  bodies  attract  each  other  with  a  force  which  is  in 
direct  proportion  to  the  amount  of  matter  which  they  contain.  The 
force  of  this  attraction,  exerted  upon  surrounding  bodies  by  the 


GENERAL   PROPERTIES   OF   MATTER  3 

earth,  becomes  sensible  as  weight,  when  the  motion  of  the  attracted 
body  toward  the  center  of  gravity  of  the  earth  is  prevented. 

In  chemical  operations  we  have  to  deal  with  three  kinds  of  weight : 
absolute,  apparent  and  specific. 

The  Absolute  Weight  of  a  body  is  its  weight  in  vacuo.  It  is 
determined  by  placing  the  entire  weighing  apparatus  under  the 
receiver  of  an  air-pump. 

The  Apparent  Weight,  or  Relative  Weight,  of  a  body  is  that 
which  we  usually  determine  with  our  balances,  and  is,  if  the  volume 
of  the  body  weighed  be  greater  than  that  of  the  counter-poising 
weights,  less  than  its  true  weight.  Every  substance  in  a  liquid  or 
gaseous  medium  suffers  a  loss  of  apparent  weight  equal  to  that  of 
the  volume  of  the  medium  so  displaced.  For  this  reason  the  appar- 
ent weight  of  some  substances  may  be  a  minus  quantity.  Thus,  if 
the  air  contained  in  a  vessel  suspended  from  one  arm  of  a  poised 
balance  be  replaced  by  hydrogen,  that  arm  of  the  balance  to  which 
the  vessel  is  attached  will  rise,  indicating  a  diminution  in  weight. 

Energy  is  the  capacity  of  matter  for  doing  work.  Energy  in- 
cludes both  that  exertion  which  is  doing  work,  which  is  known  as 
actual  or  kinetic  energy,  and  that  capacity  to  do  work  which  is 
known  as  possible  or  potential  energy.  The  relative  amounts  of  the 
two  forms  change  constantly,  but  their  sum  is  a  constant  quantity; 
i^e.,  energy,  like  matter,  can  neither  be  created  nor  destroyed. 

^The  Specific  Weight,  or  Specific  Gravity,  or  Relative  Density  of 
a  substance  is  the  weight  of  a  given  volume  of  the  substance  as  com- 
pared with  the  weight  of  an  equal  volume  of  some  substance,  accepted 
as  a  standard  of  comparison,  under  like  conditions  of  temperature 
and  pressure.  The  sp.  gr.  of  solids  and  liquids  are  referred  to  water, 
and  are  usually  determined  at  15  °C. ;  those  of  gases  to  air  or  to 
hydrogen. 

In  expressing  the  sp.  gr.  of  heavy  liquids,  the  weight  of  one  cc. 
of  water  is  taken  as  the  unit.  Thus  the  sp.  gr.  of  sulphuric  acid 
being  1.84,  1  cc.  of  water  weighing  1  gm.,  1  cc.  of  sulphuric  acid 
weighs  1.84  gms.  For  light  liquids  one  liter  of  water  is  the  unit.  Thus 
1  liter  of  a  liquid  of  sp.  gr.  1026  weighs  1026  gms.,  or  1.026  kg. 
In  metric,  therefore,  the  weight  of  1  cc.,  or  of  1  liter  of  a  liquid 
represents  its  specific  gravity. 

The  absolute  density  of  a  body  is  the  ratio  between  its  volume 

and  its  weight,  and  is  obtained  by  the  formula  D=^,  in  which  D 
is  the  density,  P  the  weight,  and  V  the  volume.  Clearly,  also  P=VD, 
and  V=^. 

When  V  is  taken  as  the  unit  of  volume  the  equation  D=—  be- 
comes D=P;  i.  e.y  the  absolute  density  of  a  substance  is  the  weight  of 


4  TEXT-BOOK   OF   CHEMISTRY 

unit  volume  of  that  substance.  But  as  the  weight  of  a  given  volume 
of  a  substance,  particularly  in  the  liquid  or  aeriform  state,  varies 
with  differences  of  temperature  and  of  pressure,  a  definite  tempera- 
ture and  pressure  have  been  arbitrarily  selected  as  constituting 
normal  conditions.  The  temperature  is  0°C.,  and  the  pressure  that 
of  a  column  of  mercury  76  centimeters  high  at  45°  latitude. 

Pressures  are  measured  either  by  the  height  of  a  column  of  mer- 
cury which  the  pressure  will  sustain  in  opposition  to  gravity,  in  cm. 
or  mm. ;  or  in  atmospheres,  one  atm.  being  the  pressure  which  will 
sustain  a  column  of  mercury  of  the  average  height  of  the  barometer ; 
i.  e.,  760  mm.  As  the  specific  gravity  (below)  of  mercury  is  13.6  at 
0°C.,  1  cc.  of  mercury  weighs  13.6  gms.,  and  each  mm.  of  mercurial 
column  is  equivalent  to  a  pressure  of  1.36.  per  sq.  cm.,  and  one 
atm.  of  pressure  is  equal  to  1033.6  gms.  per  sq.  cm. 

The  specific  volume  of  a  substance  (Vs)  is  the  reciprocal  of  its 

absolute  density:  Vs=0,  and  is  the  volume,  in  cc.,  which  one  gram 
occupies  under  normal  conditions.  Thus  for  hydrogen:  .•jnrJTjr=lllll 
cc.,  or  11.11  L.,  for  oxygen:  .-mnVs?  =699.7  cc.,  and  for  air: 
.inn1™  =773.4  cc. 

States  of  Matter. — Matter  exists  in  the'  three  forms  of  solid, 
liquid  and  gas  (or  vapor).  The  term  fluid  applies  to  both  liquids 
and  gases;  the  former  being  distinguished  as  incompressible,  the 
latter  as  compressible  fluids. 

Cohesion  is  the  force  by  which  molecules  of  the  same  kind  are 
held  together.  It  is  most  active  in  solids,  which  therefore  have 
definite  shape  and  magnitude.  In  liquids  it  is  much  less  active,  yet 
sufficient  to  maintain  a  definite  magnitude  of  the  liquid,  but  it  is 
in  part  overcome  by  gravity,  which  causes  the  liquid  to  assume  the 
shape  of  the  containing  vessel.  In  gases  cohesion  is  almost  nil ; 
therefore,  the  shape  and  volume  of  any  gas  are  those  of  the  containing 
vessel.  Cohesion  diminishes  with  the  addition  of  heat;  therefore, 
by  adding  heat  to  a  solid  it  is,  if  not  decomposed,  converted  into  a 
liquid  and  then  into  a  gas. 

SPECIAL  PROPERTIES  OF  SOLIDS,  LIQUIDS  AND  GASES. 

Crystallization. — Solid  substances  exist  in  two  forms,  amor- 
phous and  crystalline.  Amorphous  substances  assume  no  geometric 
shape;  they  conduct  heat  equally  well  in  all  directions;  they  break 
irregularly;  and,  if  transparent,  allow  light  to  pass  through  them 
equally  well  in  all  directions.  A  solid  in  the  crystalline  form  has 
a  definite  geometrical  shape;  conducts  heat  more  readily  in  some 
directions  than  in  others;  when  broken,  separates  in  certain  direc- 
tions, called  planes  of  cleavage,  more  readily  than  in  others;  and 
modifies  the  course  of  luminous  rays  passing  through  it  differently 
when  they  pass  in  certain  directions  than  when  they  pass  in  others. 


CRYSTALLIZATION  5 

Crystals  are  formed  in  one  of  four  ways:  1.  An  amorphous  sub- 
stance, by  slow  and  gradual  modification,  may  assume  the  crystalline 
form;  as  vitreous  arsenic  trioxide  (q.  v.)  passes  to  the  crystalline 
variety.  2.  A  fused  solid,  on  cooling,  crystallizes;  as  bismuth. 
3.  When  a  solid  is  sublimed  it  is  usually  condensed  in  the  form  of 
crystals.  Such  is  the  case  with  arsenic  trioxide.  4.  The  usual  method 
of  obtaining  crystals  is  by  the  evaporation  of  a  solution  of  the  sub- 
stance. If  the  evaporation  be  slow  and  the  solution  at  rest,  the 


FIG.  1. 


crystals  are  large  and  well-defined.  If  the  crystals  separate  by  the 
sudden  cooling  of  a  hot  solution,  especially  if  it  be  agitated  during 
the  cooling,  they  are  small. 

Most  crystals  may  be  divided  by  imaginary  planes  into  equal 
symmetrical  halves.  Such  planes  are  called  planes  of  symmetry. 
Thus  in  the  crystals  in  Fig.  1  the  planes  ab  ab,  ac  ac,  and  be  be  are 
planes  of  symmetry. 

When  a  plane  of  symmetry  contains  two  or  more  equivalent  linear 


J 


FIG.  2. 


directions  passing  through  the  center,  it  is  called  the  principal  plane 
of  symmetry;  as  in  Fig.  2  the  plane  ab  ab,  containing  the  equal 
linear  directions  aa  and  bb. 

Any  normal  erected  upon  a  plane  of  symmetry,  and  prolonged  in 
both  directions  until  it  meets  opposite  parts  of  the  exterior  of  the 


6 


TEXT-BOOK   OF   CHEMISTRY 


crystal,  at  equal  distances  from  the  plane,  is  called  an  axis  of 
symmetry. 

The  axis  normal  to  the  principal  plane  is  the  principal  axis. 
Thus  in  Fig  2,  aa,  bb,  and  cc  are  axes  of  symmetry,  and  cc  is  the 
principal  axis. 

Upon  the  relations  of  these  imaginary  planes  and  axes  a  classifica- 
tion of  all  crystalline  forms  into  six  systems  has  been  based. 

I.  The  Cubic,  Regular,  or  Monometric  System. — The  crystals 
of  this  system  have  three  equal  axes,  aa,  bb,  cc,  Fig.  1,  crossing  each 
other  at  right  angles.     The  simple  forms  are  the  cube;  and  its  de- 
rivatives, the  octahedron,  tetrahedron,  and  rhombic  dodecahedron. 
The  crystals  of  this  system  expand  equally  in  all  directions  when 
heated,  and  are  not  doubly  refracting. 

II.  The  Right  Square  Prismatic,  Pyramidal,  Quadratic,  Tetrag- 
onal, or  Dimetric  System  contains  those  crystals  having  three  axes 
placed  at  right  angles  to  each  other — two  as  aa  and  bb,  Fig.  2,  being 
equal  to  each  other  and  the  third,  cc,  either  longer  or  shorter.     The 
simple  forms  are  the  right  square  prism  and  the  right  square  based 


, IA 


FIG.  3. 

octahedron.  The  crystals  of  this  system  expand  equally  only  in  two 
directions  when  heated.  They  refract  light  doubly  in  all  directions, 
except  through  one  axis  of  single  refraction. 

III.  The  Rhombohedral  or  Hexagonal  System  includes  crystals 
having  four  axes,  three  of  which  aa,  aa,  aa,  Fig.  3,  are  of  equal 
length  and  cross  each  other  at  60°  in  the  same  plane;  to  which  plane 
.the  fourth  axis,  cc,  longer  or  shorter  than  the  others,  is  at  right 
angles.  The  simple  forms  are  the  regular  six-sided  prism,  the 
regular  dodecahedron,  the  rhombohedron,  and  the  scalenohedron. 


CRYSTALLIZATION  7 

These  crystals  expand  equally  in  two  directions  when  heated,  and 
refract  light  singly  through  the  principal  axis,  but  in  other  directions 
refract  it  doubly. 

IV.  The  Rhombic,  Right  Prismatic,  or  Trimetric  System.— The 
axes  of  crystals  of  this  system  are  three  in  number,  all  at  right  angles 
to  each  other,  and  all  of  unequal  length.    Fig.  2  represents  crystals 
of  this  system,  supposing  aa,  bb,  and  cc  to  be  unequal  to  each  other. 
The    simple    forms   are   the   right   rhombic    octahedron,   the   right 
rhombic  prism,  the  right  rectangular  octahedron,  and  the  right  rec- 
tangular prism.     The  crystals  of  this  system,  like  those  of  the  two 
following,  have  no  true  principal  plane  or  axis. 

V.  The  Oblique,  Monosymmetric,  or  Monoclinic  System. — The 
crystals  of  this  system  have  three  axes,  two  of  which,  aa,  and  cc. 
Fig.  4,  are  at  right  angles ;  the  third,  bb,  is  perpendicular  to  one  and 


FIG.  4. 


oblique  to  the  other.  They  may  be  equal  or  all  unequal  in  length. 
The  simple  forms  are  the  oblique  rectangular  and  oblique  rhombic 
prism  and  octahedron. 

VI.  The  Doubly  Oblique,  Asymmetric,  Triclinic,  or  Anorthic 
System  contains  crystals  having  three  axes  of  unequal  length,  cross- 
ing each  other  at  angles  not  right  angles ;  Fig.  4,  aa,  bb,  and  cc  being 
unequal  and  the  angles  between  them  other  than  90°. 

The  crystals  of  the  fourth,  fifth,  and  sixth  systems,  when  heated, 
expand  equally  in  the  directions  of  their  three  axes.  They  refract 
light  doubly  except  in  two  axes. 

Secondary  Forms. — The  crystals  occurring  in  nature  or  produced 
artificially  have  some  one  of  the  forms  mentioned  above,  or  some 
modification  of  those  forms.  These  modifications,  or  secondary 
forms,  may  be  produced  by  symmetrically  removing  the  angles  or 
edges,  or  both  angles  and  edges,  of  the  primary  forms.  Thus,  by 
progressively  removing  the  angles  of  the  cube,  the  secondary  forms 
shown  in  Fig.  5  are  produced. 

It  sometimes  happens  in  the  formation  of  a  derivative  form  that 
alternate  faces  are  excessively  developed,  producing  at  length  entire 


8 


TEXT-BOOK   OF   CHEMISTRY 


obliteration  of  the  others,  as  shown  in  Fig.  6.  Such  crystals  are 
said  to  be  hemihedral.  They  can  be  developed  only  in  a  system 
having  a  principal  axis. 

Isomorphism. — In  many  instances  two  or  more  substances  crystal- 
lize in  forms  identical  with  each  other,  and,  in  most  cases,  such 
substances  resemble  each  other  in  their  chemical  constitution.  They 
are  said  to  be  isomorphous.  This  identity  of  crystalline  form  does 
not  depend  so  much  upon  the  nature  of  the  elements  themselves,  as 


FIG.  5. 


FIG.  6. 

upon  the  structure  of  the  molecule.  The  protoxide  and  peroxide  of 
iron  do  not  crystallize  in  the  same  form,  nor  can  they  be  substituted 
for  each  other  in  reactions  without  radically  altering  the  properties  of 
the  resultant  compound.  On  the  other  hand,  all  that  class  of  salts 
known  as  alums  are  isomorphous.  Not  only  are  their  crystals  iden- 
tical in  shape,  but  a  crystal  of  one  alum,  placed  in  a  saturated 
solution  of  another,  grows  by  regular  deposition  of  the  second  upon 
its  surface.  Other  alums  may  be  subsequently  added  to  the  crystal,  a 
section  of  which  will  then  exhibit  the  various  salts,  layer  upon  layer. 

Dimorphism. — Although  most  substances  crystallize,  if  at  all,  in 
one  simple  form,  or  in  some  of  its  modifications,  a  few  bodies  are 
capable  of  assuming  two  crystalline  forms,  belonging  to  different 
systems.  Such  are  said  to  be  dimorphous.  Thus,  sulphur,  as  obtained 
by  the  evaporation  of  its  solution  in  carbon  disulphide,  forms  octa- 
hedra;  when  obtained  by  cooling  melted  sulphur  the  crystals  are 
oblique  prisms.  Occasional  instances  of  trimorphism,  of  the  forma- 
tion of  crystals  belonging  to  three  different  systems  by  the  same  sub- 
stance, are  also  known. 

Many  substances  on  assuming  the  crystalline  form,  combine  with 
a  certain  amount  of  water  which  exists  in  the  crystal  in  a  solid 
combination.  Thus  nearly  half  of  the  weight  of  crystallized  alum 
is  water.  This  water  is  called  water  of  crystallization,  and  is  neces- 
sary to  the  maintenance  of  the  crystalline  form,  and  frequently  to 
the  color.  If  blue  vitriol  is  heated,  it  loses  its  water  of  crystalliza- 


DIFFUSION   OF   LIQUIDS  9 

tion,  and  is  converted  into  an  amorphous,  white  powder.  Some 
crystals  lose  their  water  of  crystallization  on  mere  exposure  to  the 
air.  They  are  then  said  to  effloresce.  Usually,  however,  they  only 
lose  their  water  of  crystallization  when  heated  (p.  64). 

Allotropy. — Dimorphism  apart,  a  few  substances  are  known  to 
exist  in  more  than  one  solid  form.  These  varieties  of  the  same 
substance  exhibit  different  physical  properties,  while  their  chemical 
qualities  are  the  same  in  kind,  but  differ  in  their  degrees  of  activity. 
Such  modifications  are  said  to  be  allotropic.  One  or  more  allotropic 
modifications  of  a  substance  are  usually  crystalline,  the  other  or 
others  amorphous  or  vitreous.  Sulphur,  for  example,  exists  not  only 
in  two  dimorphous  varieties  of  crystals,  but  also  in  a  third,  allotropic 
form,  in  which  it  is  flexible  and  amorphous.  Carbon  exists  in  three 
allotropic  forms :  two  crystalline,  the  diamond  and  graphite ;  the  third 
amorphous.  For  other  examples  of  allotropy,  see  ozone,  phosphorus, 
and  silicon. 

In  passing  from  one  allotropic  modification  to  another,  a  sub- 
stance absorbs  or  gives  out  heat. 

Diffusion  of  Liquids — Dialysis. — If  a  liquid  is  carefully  floated 
upon  the  surface  of  a  heavier  liquid,  with  which  it  is  capable  of  mix- 
ing, two  distinct  layers  are  at  first  formed.  But,  even  at  perfect 
rest,  mixing  of  the  two  liquids,  in  opposition  to  gravity,  will  begin 
immediately,  and  progress  slowly  until  the  two  liquids  have  diffused 
into  each  other  to  form  a  single  liquid  whose  composition  and  density 
are  the  same  throughout. 

If,  in  place  of  bringing  the  two  liquids  into  direct  contact,  they 
are  separated  from  each  other  by  a  membrane  of  goldbeater's  skin, 
each  will  pass  through  the  membrane  into  the  other,  a  phenomenon 
called  osmosis,  but  they  do  not  pass  with  equal  rapidity.  Thus,  if 
the  two  liquids  are  alcohol  and  water,  one  part  of  alcohol  will  pass  in 
one  direction  while  4.2  parts  of  water  pass  in  the  other.  This  rela- 
tion, as  compared  with  water,  is  the  osmotic  equivalent  of  the  sub- 
stance, and  may  be  determined  not  only  for  liquids,  but  also  for 
solids  in  solution. 

If  a  layer  of  a  pure  solvent  (p.  14)  is  similarly  floated  upon  a 
solution  of  a  solid  in  the  same  liquid,  as  water  upon  a  solution  of 
sugar,  or  if  the  two  are  separated  by  a  membrane  of  parchment  paper, 
bladder,  or  other  permeable  membrane,  the  pure  solvent  will  pass 
into  the  solution,  and  the  dissolved  sugar  into  the  pure  solvent  until 
the  two  liquids  have  the  same  concentration,  i.  e.,  contain  the  same 
quantity  of  dissolved  substance  in  unit  volume  throughout.  (See 
solution,  p.  14.) 

Solids  in  solution  differ  in  the  rapidity  and  completeness  with 
which  they  undergo  osmosis,  or  dialyse.  Substances  which  crystallize, 
crystalloids,  dialyse  easily  and  with  relative  rapidity;  those  which 
do  not  form  crystals,  colloids,  do  not  dialyse,  or  do  so  with  extreme 


10 


TEXT-BOOK   OF   CHEMISTRY 


slowness.  Advantage  is  taken  of  this  difference  to  separate  crystal- 
loids from  colloids,  as  salt  from  albumin.  The  solution  of  the  two 
substances  is  placed  in  the  inner  vessel  of  a  dialyser  (Fig.  7), 
whose  bottom  consists  of  a  layer  of  parchment  paper,  and  the  outer 
vessel  is  filled  with  the  pure  solvent,  water,  which  is  frequently 
changed  as  the  crystalloid  collects  in  it.  Or  a  section  of  tubing 
made  of  parchment  paper,  bent  into  a  U  shape,  may  be  used  as  the 
inner  vessel,  and  suspended  in  water.  Plates  of  porous  earthenware 
may  also  be  used  for  dialysis  of  liquids  which  would  attack  an  animal 

or  vegetable  membrane,  but 
their  action  is  much  slower. 
Semipermeable  membranes 
are  membranes  which  are  per- 
meable to  certain  diffusible 
substances,  but  not  to  others, 
usually  permeable  to  water 
but  not  to  certain  substances 


in  solution  in  it.  Such  mem- 
branes exist  in  animal  and 
vegetable  nature  and  are 
formed  artificially.  Pfeffer's 
membrane  is  obtained  by 
placing  a  solution  of  cupric 
FIG.  7.  .  sulphate  in  a  jar  of  porous 

earthenware,    which    is   then 

immersed  in  a  solution  of  potassium  ferrocyanide.  A  delicate,  gela- 
tinous film  of  cupric  ferrocyanide  forms  in  the  walls  of  the  jar  where 
the  two  solutions  come  in  contact,  which  constitutes  the  semipermeable 
membrane,  permeable  to  water  and  to  saltpeter  dissolved  in  water, 
but  not  to  sugar  or  to  many  other  substances  in  aqueous  solution. 
(See  Osmosis,  p.  9.) 

Gases  when  subjected  to  pressure  diminish  in  volume  progres- 
sively to  an  amount  limited  only  by  their  passage  to  the  form  of 
liquid  (p.  15).  When  relieved  of  pressure  they  expand  to  an  un- 
limited extent.  They  have,  therefore,  the  volume  of  the  containing 
vessels,  upon  whose  walls  they  exert  a  pressure  corresponding  to  that 
to  which  they  are  themselves  subjected,  and  in  all  parts  of  which 
they  have  the  same  density. 

Boyle-Mariotte  Law. — If  any  gas,  maintained  at  a  constant  tem- 
perature, is  contained  in  a  vessel  whose  capacity  may  be  altered,  as 
by  a  piston,  the  pressure  exerted  by  the  gas  is  found  to  be  doubled 
when  the  capacity  of  the  vessel  is  reduced  to  one-half;  and  corre- 
sponding variations  of  pressure  are  observed  with  other  changes  in 
volume : 

The  temperature  remaining  the  same,  the  volume  of  a  given  quan- 
°f  9as  is  inversely  as  the  pn\\///v    (Boyle-Mariotte  Law).     Or: 


HEAT  11 

vp=constant.  It  also  follows  that  the  density  of  a  gas  is  proportion- 
ate to  the  pressure. 

Absorption  of  Gases. — Physical  solution  (p.  14)  of  a  gas  in  a 
liquid  is  called  absorption.  The  absorption  of  gases  by  liquids  obeys 
the  following  laws: 

Tlie  weight  of  a  gas  absorbed  by  unit  volume  of  a  given  liquid  is 
proportionate  to  the  gas  pressure  (Henry's  law). 

The  quantity  of  gas  absorbed  diminishes  with  increase  of  tem- 
perature. 

The  quantity  of  a  gas  which  a  liquid  can  absorb  is  independent  of 
the  nature  and  quantity  of  other  gases  which  it  may  already  hold  in 
solution. 

Some  solid  substances  also  absorb  certain  gases.  Sometimes  such 
absorption  is  a  physical  act,  when  it  is  referred  to  as  condensation 
or  absorption.  Thus  charcoal  condenses  about  90  times  its  volume  of 
ammonia.  In  other  cases  it  is  a  chemical  combination,  as  when 
caustic  potash  absorbs  carbon  dioxide. 

SOME  PHYSICAL  ACTIONS  OF  CHEMICAL  INTEREST. 

HEAT. 

The  Effects  of  Heat  upon  a  body  are  in  doing  internal  work:  to 
raise  its  temperature,  to  increase  its  volume,  to  change  its  state  of 
aggregation,  or  to  cause  atomic  rearrangement,  i.  e.y  chemical  change, 
or  in  doing  external  work:  in  exerting  pressure,  or  in  transmitting 
heat  to  surrounding  bodies. 

Temperature. — The  temperature  of  a  body  is  the  extent  to  which 
it  can  impart  sensible  heat  to  surrounding  bodies.  It  is  not  to  be 
confounded  with  the  amount  or  quantity  of  heat  which  the  body  con- 
tains. A  block  of  ice  just  beginning  to  melt  and  the  same  weight 
of  water  just  beginning  to  freeze  have  the  same  temperature;  but 
heat  must  be  added  to  the  ice  to  continue  its  fusion  and  subtracted 
from  the  water  to  continue  its  solidification,  while  during  both 
processes  the  temperature  remains  the  same  in  each. 

Thermometers  are  instruments  for  the  measurement  of  tempera- 
ture. They  are  usually  glass  tubes  having  a  bulb  blown  at  one 
end  and  closed  at  the  other,  the  bulb  and  part  of  the  tube  being  filled 
with  mercury  or  with  alcohol,  whose  contraction  or  expansion  indi- 
cates a  fall  or  rise  of  temperature.  The  alcoholic  thermometer  is  used 
for  measuring  low  temperatures,  and  the  mercurial  for  temperatures 
between  — 40°  and  360°  C.  For  higher  temperatures  instruments 
called  pyrometers,  based  upon  the  expansion  or  variation  of  electrical 
conductance  of  solids,  are  used. 

In  every  thermometer  there  are  two  fixed  points,  determined  by 
experiment.  The  lower,  or  freezing  point,  is  fixed  by  immersing  the 
instrument  in  melting  ice,  and  marking  the  level  of  the  mercury  in 
the  tube  upon  the  glass  when  it  has  become  stationary.  The  higher, 


12 


TEXT-BOOK   OF   CHEMISTRY 


or  boiling  point,  is  similarly  fixed  by  suspending  the  instrument  in 
the  steam  from  boiling  water.  The  instrument  is  then  graduated 
according  to  one  of  three  scales: "the  Celsius,  or  Centigrade,  the 
Fahrenheit,  and  the  Reaumur.  The  freezing  point  is  marked  0°  in 
the  Centigrade  and  Reaumur  scales,  and  32  °  in  the  Fahrenheit.  The 
boiling  point  is  marked  100°  in  the  Centigrade,  212°  in  the  Fahren- 
heit, and  80°  in  the  Reaumur  scale  (Fig. 
8).  The  space  between  the  fixed  points 
is  divided  into  100  equal  degrees  in  the 
Centigrade  scale,  into  180°  in  the 
Fahrenheit,  and  into  80°  in  the  Reau- 
mur. Five  degrees  Centigrade  are 
therefore  equal  to  nine  degrees  Fahren- 
heit. 

To  convert  readings  in  one  scale  into 
terms  of  another  the  following  formulae 
are  used : 

Centigrade  to  Fahrenheit:  Multiply 
by  9,  divide  by  5,  and  add  32.  Ex- 
ample: 50  °C.X9  =  450-f-5  =  90+32  = 
122°=Ans. 

Fahrenheit  to  Centigrade:  Subtract 
32,  multiply  by  5,  and  divide  by  9. 
Example:  5°F.— 32=  —27X5=  —135 
4-9=  — 15°=Ans. 

The  Centigrade  scale  is  the  one  now 
exclusively  used  for  scientific  work,  and 
is  the  only  one  referred  to  throughout 
this  volume. 

Measure  of  Heat. — Heat  is  measured 

by  its  effect  in  raising  the  temperature  of  a  given  weight  of  water 
through  a  given  number  of  degrees  of  temperature.  Several  units 
have  been  used,  and,  unless  definitely  stated,  may  easily  lead  to 
confusion. 

The  calorie,  or  therm,  or  small  calorie,  or  gram-calorie  (cal.)  is 
the  amount  of  heat  required  to  raise  the  temperature  of  one  gram  of 
water  from  0°  to  1°C.  (or  from  4°  to  5°C.).  The  rational  calorie 
(K)  is  the  amount  of  heat  required  to  raise  the  temperature  of  one 
gm.  of  water  from  0°  to  100 °C.,  and  is  nearly  equal  to  100  cal.  Tin- 
large  calorie,  or  kilogram  calorie  (kg:cal.),  is  based  upon  the  raise 
of  temperature  of  one  kilogram  of  water  from  4°  to  5°C.,  and  is 
equal  to  1000  cal. 

Changes  in  Volume  Caused  by  Heat. — As  a  rule,  all  substances 
increase  in  volume  when  heated,  and  diminish  in  volume  on  losing 
heat.  There  are,  however,  some  exceptions  to  this  rule. 

Solids  and  liquids  change  only  slightly  in  volume  by  heating  or 


FIG.  8. 


HEAT  13 

cooling.'  Thus  the  coefficient  of  linear  expansion,  or  ratio  of  varia- 
tion in  length,  of  steel  is  .0000124,  and  the  coefficient  of  cubic 
expansion,  of  variation  in  volume  of  mercury  is  .00018  for  1°C. 
Water  on  being  cooled  contracts  until  its  temperature  is  4°C.,  be- 
tween which  and  0°  it  again  expands;  4°C.  is,  therefore,  the  tem- 
perature of  maximum  density  of  water. 

The  changes  in  volume  of  gases  by  heat  are  of  much  greater 
theoretical  importance  than  those  in  solids  and  liquids. 

We  have  seen  that  the  volume  of  gas  varies  with  the  pressure  in 
obedience  to  the  law:  VP=constant.  This  is  only  true  if  the  tem- 
perature remain  constant.  With  variation  in  temperature  the  volume 
of  a  gas  varies  according  to 

The  Dalton — Gay-Lussac  Law : — The  pressure  remaining  con- 
stant, the  volume  of  a  gas  varies  directly  with  the  absolute  tempera- 
ture (see  below).  And,  conversely,  if  the  volume  remain  constant,  the 
pressure  varies  directly  with  the  temperature. 

The  Law  of  Charles  is  to  the  effect  that  all  gases  have  the  same 
coefficient  of  expansion. 

Absolute  Zero — Absolute  Temperature. — As  gases  contract  by 
^73  of  their  volume  with  each  degree  of  diminution  of  temperature, 
a  unit  volume  of  gas  at  0°  on  continuous  cooling  would  occupy  zero 
volume  at  — 273°.  As  it  is  assumed  that  at  that  temperature  a  gas 
contains  no  heat  — 273°  is  taken  as  the  absolute  zero,  and  degrees 
of  absolute  temperature  are  from  that  point:  T=273-ft.  Thus, 
if  the  observed  temperature,  t,  be  54  CC.  the  absolute  temperature, 
T,  is  273+54=327.  No  gas  is  known  to  exist  at  so  low  a  tempera- 
ture as  — 273  ° ;  the  most  resistant,  hydrogen,  forms  a  liquid  which 
boils  at  — 252.5°,  and  this  temperature  can  only  be  slightly  lowered 
by  reducing  the  pressure.  The  lowest  temperature  yet  attained  is 
—263°. 

Change  of  State. — The  state  of  aggregation  of  matter  depends 
partly  upon  the  pressure  to  which  it  is  subjected,  but  principally 
upon  the  amount  of  heat  which  it  contains.  If  chemical  decomposi- 
tion does  not  occur,  when  heat  is  added  to  a  solid  the  motion  of  its 
molecules  becomes  more  rapid,  and  their  cohesion  becomes  less,  until 
the  solid  becomes  a  liquid.  With  the  addition  of  more  heat  the 
molecules  are  more  widely  separated,  their  cohesion  is  reduced  to  the 
minimum,  and  the  liquid  becomes  a  vapor.  The  reverse  order  of 
change  is  produced  by  abstraction  of  heat,  popularly  referred  to  as 
"cooling." 

Solids  assume  the  liquid  form  by  fusion  or  by  solution. 

Fusion. — When  a  solid,  not  decomposed  by  heat,  is  sufficiently 
heated  it  fuses,  or  melts.  Substances  which  withstand  a  high  tam- 
perature  without  fusion  are  said  to  be  refractory.  Every -substance 
begins  to  fuse  at  a  certain  temperature,  which  is  always  the  same 
for  a  given  substance,  the  pressure  remaining  constant,  and  which 


14  TEXT-BOOK   OF   CHEMISTRY 

remains  the  same  until  fusion  is  complete,  whatever  the  intensity  of 
the  heat  applied.  This  temperature  is  called  the  fusing  point  of  the 
substance,  and  is  one  of  the  characters  depended  upon  for  its  identi- 
fication, and  as  a  test  of  its  purity.  Some  substances  pass  by  imper- 
ceptible changes  of  gradual  softening  from  the  condition  of  solid  to 
that  of  liquid,  the  temperature  rising  the  while,  and  therefore  have 
no  true  fusing  point ;  such  are  iron  and  glass. 

The  fusing  point  is  only  slightly  influenced  by  the  pressure. 
That  of  substances  which  contract  on  fusion  is  slightly  lowered  by 
increase  of  pressure,  and  that  of  those  which  expand  on  fusion  is 
slightly  raised. 

Latent  heat. — As  during  the  fusion  of  a  solid  there  is  no  increase 
of  temperature,  notwithstanding  that  heat  is  being  constantly  com- 
municated to  the  body,  the  insensible  heat  so  added,  which  really 
does  work,  is  said  to  become  latent.  Each  substance  has  its  own 
latent  heat,  or  latent  heat  of  fusion,  as  it  is  also  called.  Thus,  if 
a  pound  of  water  at  0°C.  is  placed  in  one  vessel,  and  in  another 
similar  vessel  a  pound  of  ice  at  0°C.,  and  the  two  vessels  then 
immersed  in  a  large  vessel  of  hot  water  until  the  ice  is  melted,  the 
temperature  of  the  melted  ice  will  be  found  to  be  0°C.,  while  the 
temperature  of  the  water,  previously  at  0°  will  be  found  to  be 
79.25°  C. ;  therefore  the  amount  of  heat  which  became  latent  in 
melting  the  ice  was  79.25°. 

Solution. — A  solid,  liquid  or  gas  is  said  to  dissolve,  or  to  form  a 
solution  in  a  liquid,  when  the  two  substances  form  a  homogeneous 
liquid.  The  molecules  of  the  dissolved  substance,  the  solute,  are 
assumed  to  be  uniformly  distributed  among  the  molecules  of  the 
liquid,  which  is  called  the  solvent. 

The  act  of  solution  may  be  a  purely  physical  process,  without 
chemical  action  between  the  solute  and  the  solvent,  in  which  case  it 
is  referred  to  as  physical  or  simple  solution;  or  it  may  consist  of 
two  distinct  acts,  one  a  chemical  action  between  solute  and  solvent, 
and  the  other  the  physical  solution  of  the  new  substance  thus  pro- 
duced, in  which  case  it  is  called  chemical  solution.  A  physical  solu- 
tion contains  the  original  substance,  which,  if  a  solid,  can  be  recov- 
ered unchanged  by  evaporation  of  the  solution,  as  cupric  nitrate  from 
a  solution  of  that  salt,  however  obtained.  A  chemical  solution  is,  in 
fact,  a  physical  solution  of  the  new  substance  formed  in  the  reaction, 
as  cupric  nitrate  is  also  left  on  evaporation  of  a  solution  of  copper  in 
nitric  acid. 

The  quantity  of  a  single  solid  which  can  be  dissolved  in  a  pure 
solvent,  water  for  instance,  depends  upon  an  inherent  relation  be- 
tween solvent  and  solute,  called  the  solubility,  and  upon  the  tempera- 
ture. The  solubility  of  a  solid  is  one  of  its  distinguishing  characters, 
and  each  solid  has  a  definite  solubility  in  a  given  liquid  at  a  given 
temperature.  When  no  solvent  is  mentioned,  water  is  understood. 


HEAT  15 

Some,  solids,  such  as  calcium  chloride,  are  so  readily  soluble  in 
water  that  they  absorb  sufficient  from  the  air  to  form  a  solution. 
They  'are  then  said  to  deliquesce. 

The  solubility  of  most  solids  increases  with  rise  of  temperature. 
With  some  the  increase  of  solubility  is  proportionate  to  the  rise  of 
temperature,  with  others  the  solubility  is  very  slightly  affected  by 
variation  of  temperature,  and  with  others  there  is  a  certain  tempera- 
ture of  maximum  solubility,  above  which  it  again  diminishes. 

A  solution  containing  as  much  of  the  solute  as  it  is  capable  of 
dissolving  at  the  existing  temperature  is  said  to  be  saturated.  If 
made  at  high  temperature  it  is  said  to  be  a  hot  saturated,  and  if  at 
the  ordinary  temperature  a  cold  saturated  solution.  If  a  hot  satu- 
rated solution,  or  one  containing  more  solid  than  the  liquid  is  capable 
of  dissolving  at  a  lower  temperature,  be  cooled,  the  solid  usually  sep- 
arates in  the  crystalline  form.  But  if,  in  the  case  of  certain  sub- 
stances, the  solution  is  allowed  to  cool  while  undisturbed,  no  crystal- 
lization occurs,  and  the  solution  at  the  lower  temperature  contains  a 
larger  amount  of  the  solid  than  it  could  dissolve  at  that  temperature. 
It  is  then  said  to  be  supersaturated.  If  a  given  quantity  of  liquid  be 
brought  in  contact  with  a  quantity  of  solid  less  than  it  can  dissolve 
at  the  existing  temperature,  the  solid  dissolves  completely  to  form 
an  unsaturated  solution;  while  if  it  be  in  contact  with  any  excess 
of  the  solid,  such  excess  remains  undissolved,  and  has  no  influence 
upon  the  solution  so  long  as  the  temperature  remains  constant.  The 
solubility  of  solids  is  also  influenced  by  the  pressure,  but  to  so  trifling 
an  extent  that  it  may  be  disregarded.  Dilute  solutions  are  such  as 
contain  very  small  quantities  of  the  solutes. 

Congelation  is  the  passage  of  a  substance  from  the  liquid  to  the 
solid  form.  It  is  the  reverse  of  fusion,  and  takes  place  at  the  same 
fixed  temperature,  which  also  remains  constant  until  fusion  is  com- 
plete. This  temperature  is  called  the  freezing  point  of  the  substance. 

Vaporization. — The  passage  of  a  liquid  to  an  aeriform  state  may 
take  place  from  the  surface  of  the  liquid  only,  when  the  process  is 
called  evaporation,  or  it  may  take  place  throughout  the  mass  of  the 
liquid,  when  it  is  called  ebullition,  or  boiling.  Liquids  which 
evaporate  readily,  as  alcohol,  chloroform,  ether,  are  distinguished  as 
volatile  liquids;  while  liquids  which  do  not  evaporate,  like  the  fixed 
oils  and  glycerol,  are  called  fixed  liquids. 

Gases  and  Vapors. — All  aeriform  bodies  have  been  converted 
into  liquids  under  the  combined  influence  of  cold  and  pressure. 

Aeriform  bodies  exist  in  two  conditions,  dependent  upon  the 
temperature.  For  each  gas  there  is  a  certain  temperature,  different 
for  different  gases,  at  and  below  which  the  gas  can  be  converted  into 
a  liquid  by  sufficient  increase  of  pressure,  without  further  lowering 
of  temperature,  but  above  which  no  amount  of  pressure  will  cause 
liquefaction.  That  temperature  is  called  the  critical  temperature. 


16  TEXT-BOOK   OF   CHEMISTRY 

At  temperatures  above  their  critical  temperatures  aeriform  bodies  are 
gases,  below  that  temperature  they  are  vapors.  When  the  substance 
is  at  its  critical  temperature  there  is  a  certain  definite  pressure 
which  will  cause  its  liquefaction,  which  is  called  its  critical  pressure. 
For  example:  the  critical  temperature  of  carbon  dioxide  is  31.1°,  and 
its  critical  pressure  75.56  atm. 

When  a  liquid  is  heated  in  a  sealed  glass  tube  of  sufficient 
strength  to  withstand  the  high  pressure  attained,  a  temperature  is 
finally  reached  when  the  liquid  disappears,  and  the  tube  is  filled 
with  its  vapor,  which,  having  the  same  volume  and  weight  as  the 
liquid,  also  has  the  same  density.  The  temperature  at  which  this 
occurs,  190°  for  ether,  is  clearly  the  critical  temperature  of  the 
substance,  which  is  therefore  also  called  its  absolute  boiling  point, 
and  the  pressure  in  the  tube  is  its  critical  pressure.  There  is  also 
necessarily  a  critical  density,  i.  e.,  the  weight  of  unit  volume  of  the 
substance  at  its  critical  temperature  and  pressure. 

Boiling. — At  a  given  pressure  a  liquid  begins  to  boil  at  a  cer- 
tain temperature,  which  varies  in  different  liquids,  but  is  always  the 
same  in  the  same  liquid.  This  temperature  at  760  mm.  of  pressure 
is  the  boiling  point  of  the  liquid. 

The  boiling  point  remains  stationary  until  the  liquid  is  com- 
pletely volatilized,  whatever  the  degree  of  the  heat  applied. 

The  boiling  point  is  raised  by  increase  of  pressure,  and  depressed 
by  diminution  of  pressure. 

Latent  heat  of  vapor. — The  heat  required  by  a  liquid  to  convert 
it  into  a  vapor,  which  is  insensible  as  temperature,  is  the  latent 
heat  of  vapor  (p.  14). 

A  liquid,  in  evaporating,  absorbs  heat.  It  is  by  this  action  that 
the  human  body  is  cooled  by  the  evaporation  of  perspiration  from 
the  skin,  that  local  anesthesia  is  produced  by  the  evaporation  of 
very  volatile  liquids,  and  that  cold  is  produced  in  refrigerating 
machines. 

Liquefaction  or  condensation  is  the  passage  of  a  gas  or  vapor 
to  the  form  of  a  liquid.  It  is  brought  about  by  chemical  action, 
by  cooling,  and  by  compression. 

Certain  salts,  such  as  calcium  chloride,  absorb  vapor  of  water 
from  the  air  and  with  it  form  a  solution.  They  are  then  said  to 
deliquesce. 

When  vapors  are  cooled  to  a  temperature  below  the  boiling  point 
of  the  liquid  from  which  they  originated,  at  the  existing  pressure, 
they  are  condensed. 

The  process  of  distillation  consists  in  converting  a  liquid  into  a 
vapor  by  heat  and  subsequently  condensing  the  vapor  by  cooling  it. 
Distillation  under  reduced  pressure  is  frequently  resorted  to  when 
it  is  desirable  to  avoid  a  temperature  tis  high  as  the  boiling  point 
of  the  liquid.  Fractional  distillation  is  the  separation  of  liquids  of 


ELECTRICITY  17 

different  boiling  points  by  distillation  and  collection  of  the  several 
fractions  separately. 

Sublimation  is  a  process  differing  from  distillation  in  that  the 
material  acted  upon  and  the  product  are  solid.  Sublimation  may 
or  may  not  be  attended  by  fusion  of  the  original  substance.  The 
product  is  called  a  sublimate,  or,  if  in  fine  powder,  flowers. 

Specific  Heat. — Equal  weights  of  different  substances  do  not  pos- 
sess the  same  capacity  for  heat  or  thermal  capacity.  Thus  if  equal 
weights  of  water  and  of  mercury  are  exposed  to  the  same  source  of 
heat  until  the  water  shall  have  acquired  a  temperature  of  1°  C.,  the 
mercury  will  have  a  temperature  of  30°.  A  given  weight  of  water, 
therefore,  requires  30  times  as  much  heat  to  raise  its  temperature 
through  1°  as  does  an  equal  weight  of  mercury,  and  the  capacity 
for  heat  of  mercury  is  %o,  or  0.0333,  that  of  an  equal  weight  of  water. 

The  specific  heat  of  a  substance  is  the  amount  of  heat  required  to 
raise  the  temperature  of  one  kilo,  of  that  substance  through  one 
degree  Centigrade,  expressed  in  calories.  Thus,  the  specific  heat  of 
mercury  is  0.0333,  as  stated  above. 

ELECTRICITY. 

Certain  substances,  such  as  amber,  glass,  sealing-wax,  when 
rubbed  with  silk,  flannel,  etc.,  acquire  the  power  of  attracting  light 
bodies.  They  are  then  said  to  be  electrified. 

If  a  glass  rod  is  rubbed  with  silk  and  approached  to  a  pith  ball 
suspended  by  a  silk  thread  from  a  glass  support,  the  pith  ball  is 
first  attracted,  and,  after  a  short  contact  with  the  glass,  is  then 
repelled.  The  pith  ball  has  become  electrified  by  contact  with  the 
glass,  and  in  this  condition  the  two  bodies  repel  each  other.  But  if 
now  a  rod  of  sealing-wax  is  rubbed  with  flannel  and  approached  to 
the  electrified  pith  ball,  the  rod  will  attract  the  ball.  In  this  state  the 
ball  is  repelled  by  the  electrified  glass,  and  attracted  by  the  electrified 
sealing-wax.  And,  similarly,  a  pith  ball  electrified  by  contact  with 
the  electrified  sealing-wax  will  be  repelled  by  the  wax  and  attracted 
by  the  glass  rod.  There  are,  therefore,  two  kinds  of  electricity,  one 
generated  in  glass  by  friction  with  silk,  called  vitreous  or  positive 
(  +  )  electricity,  the  other  generated  in  sealing-wax  by  friction  with 
flannel,  called  resinous,  or  negative  ( — )  electricity. 

Bodies  similarly  electrified  repel  each  other,  and  bodies  differently 
electrified  attract  each  ofher. 

Insulators— Conductors— Ions.— If  two  metal  spheres,  Supported 
upon  glass  rods,  and  placed  about  a  foot  apart,  are  charged,  one  with 
positive,  and  the  other  with  negative  electricity,  the  spheres  will 
attract  each  other,  but  each  will  retain  its  charge  in  dry  air.  If,  now, 
a  glass  rod  is  brought  in  contact  with  both  spheres  at  the  same  time, 
each  still  retains  its  charge  as  before.  But  if  a  brass  rod  is  used  in 


18 


TEXT-BOOK   OF   CHEMISTRY 


place  of  the  glass  one,  the  positive  and  negative  electricities  neu- 
tralize each  other,  and  both  spheres  lose  their  charges.  Glass  is  an 
insulator,  or  non-conductor  of  electricity;  brass  is  a  conductor. 
Conductors  are  of  two  kinds:  Conductors  of  the  first  order,  such  as 
metals,  conduct  electricity  without  themselves  suffering  any  change, 
except  elevation  of  temperature.  Conductors  of  the  second  order, 
such  as  solutions  of  salts,  are  substances  from  which  their  con- 
stituents are  separated  by  the  passage  of  electricity  through  them. 
The  constituents  which  are  thus  separated  from  a  conductor  of  the 
second  order  are  called  ions  (pp.  20,  35).  Another  distinction  be- 
tween the  two  orders  of  conductors  is  that  with  those  of  the  first  order 
electrical  energy  only  is  transported,  while  with  those  of  the  second 
order  matter  (the  ions)  is  also  transported. 

Galvanic  Electricity. — The  kinetic  energy  which  is  developed  in 
chemical  solution  of  a  metal  is  manifested  in  part  as  heat,  but  also 


Zn 


i  _ 


'4- 


Zn 


H  -- 


Cu 


FIG.  9. 


FIG.  10. 


in  great  part  in  charging  the  metal  with  negative  electricity,  and 
the  solvent  with  positive  electricity.  Thus,  if  a  plate  of  pure  zinc 
is  immersed  in  pure  dilute  sulphuric  acid,  the  metal  becomes  charged 
with  negative  electricity,  and  at  the  same  time  a  part  of  the  zinc 
goes  into  solution,  its  ions  carrying  a  positive  charge  to  the  surround- 
ing liquid  (Fig.  9).  This  action  continues  for  a  very  short  time, 
until  the  electric  charge  so  produced  balances  the  "solution  pressure" 
of  the  metal,  i.  e.,  its  tendency  to  dissolve  when  all  action  ceases.  If, 
now,  a  plate  of  pure  copper  is  also  immersed  in  the  acid,  the  solu- 
tion pressure  of  this  metal  being  extremely  small,  the  copper 
simply  becomes  charged  with  positive  electricity,  and  the  surround- 
ing liquid  with  negative  electricity;  but  no  further  solution  of  the 
zinc  occurs  (Fig.  10).  If,  now,  the  two  metal^  plates  are  connected 
by  a  conducting  wire,  the  negative  electricity  of  the  zinc  and  the 
positive  of  the  copper  neutralize  each  other  along  the  conductor 
(Fig.  11),  the  electric  charges  of  the  liquid  ivcombinc,  ;ind  solution 
of  the  zinc  again  begins,  attended  by  the  generation  of  constantly 
renewed  electric  charges,  which  constantly  tend  to  neutralize  each 


ELECTRICITY 


19 


Cu 


other,  producing  an  electric  current,  which  consists  of  the  passage 
of  positive  electricity  in  one  direction,  and  of  negative  electricity  in 
the  opposite  direction. 

An  arrangement  of  metals  and  solvent  such  as  that  described  is 
called  a  galvanic  cell  or  element,  and  a  combination  of  two  or  more 
is  a  galvanic  battery. 

An  electric  current  is  produced  whenever  two  metals,  or  a  metal 
and  another  conducting  solid,  are  immersed  in  a  liquid  in  which  the 
two  solids  have  different  solution  pressures,  or  when  two  plates  of 
the  same  kind  of  metal  are  immersed  in  two  liquids  in  which  the 
metal  has  different  solution  pressures,  and  either  floated  one  upon 
the  other,  or  separated  only  by 
a  porous  diaphragm.  The  metal 
having  the  higher  solution  pres- 
sure is  the  one  which  is  dissolved 
in  the  action  of  the  galvanic  ele- 
ment, and  hence  is  the  position  of 
higher  potential.  The  other  plate 
is  the  position  of  lower  potential. 
Any  wires  or  other  conductors  at- 
tached to  the  plates  are  called 
poles,  or  leads,  or  electrodes.  The 
entire  system  of  solvent,  plates 
and  outside  conductors  is  called  an 
electric  or  galvanic  circuit.  The 

circuit  is  said  to  be  closed  when  there  is  no  break  in  its  continuity, 
and  the  current  is  free  to  pass.  It  is  said  to  be  open  when  there  is 
an  interruption  in  its  continuity,  when  the  current  ceases  to  pass. 

The  positive  electrical  current  originates  at  that  plate  having  the 
greater  solution  pressure,  i.  e.,  the  higher  potential  (the  zinc  plate, 
Fig.  11),  which  is  therefore  called  the  generating,  or  positive  plate. 
It  flows  through  the  liquid  in  the  cell  to  the  plate  of  lower  potential 
(the  copper  plate),  which  is  therefore  called  the  collecting,  or  nega- 
tive plate.  From  the  collecting  plate  the  current  passes  through  the 
outside  conductors  of  the  circuit  toward  the  generating  plate.  As 
the  positive  current  leaves  the  cell  from  the  negative  plate,  the 
electrode  connected  with  that  plate  is  of  higher  potential  than  that 
connected  with  the  generating  plate,  and  therefore  we  have  the 
apparent  anomaly  that  the  pole  connected  with  the  negative  plate  is 
called  the  positive  pole,  or  the  anode,  while  the  pole  connected  with 
the  positive  plate  is  called  the  negative  pole,  or  the  cathode,  or 
kathode.  The  positive  current,  therefore,  passing  from  the  position 
of  higher  potential  to  that  of  lower  potential,  in  many  respects 
resembles  the  flow  of  water  from  a  higher  to  a  lower  level,  or  the 
passage  of  heat  from  a  higher  to  a  lower  temperature.  The  negative 
current,  on  the  other  hand,  passes  from  lower  to  higher  potential. 


FIG.  11. 


20  TEXT-BOOK   OF   CHEMISTRY 

The  total  current  is  the  sum  of  the  passage  of  positive  charges  in  one 
direction  and  of  negative  charges  in  the  opposite  direction. 

Electromotive  Force — Resistance. — The  difference  in  potential 
of  an  electric  generator  is  referred  to  as  its  electromotive  force 
(E.  M.  R). 

The  strength  of  the  current  is  directly  as  the  E.  M.  R,  and  in- 
versely as  the  resistance,  and,  consequently,  the  current  strength 
is  the  E.  M.  F.  divided  by  the  resistance  (Ohm's  law). 

We  have  seen  that  some  substances  conduct  electricity,  while 
others  do  not.  Conductors  also  differ  in  the  degree  of  facility  with 
which  they  allow  the  current  to  pass  through  them  when  they  are  of 
equal  length  and  of  equal  cross-section.  The  resistance  of  a  con- 
ductor is  the  degree  of  opposition  which  it  offers  to  the  passage  of 
the  current,  and  the  complement  of  the  resistance  is  the  conductance 
of  the  conductor.  Eesistance  and  conductance  are  clearly  inversely 
proportionate  to  each  other.  They  depend  upon  four  factors:  1.  The 
special  property  of  conductivity  of  the  material;  2.  The  length  of 
the  conductor ;  3.  Its  cfcoss-section ;  4.  The  temperature.  The  resist- 
ance is  directly  as  the  length,  and  inversely  as  the  cross-section  of 
the  conductor.  With  metals  it  is  increased,  and  with  salt  solutions 
it  is  diminished  by  elevation  of  temperature.  In  considering  the 
resistance  of  a  galvanic  circuit  we  have  to  deal  with  both  internal 
resistance,  i.  e.,  that  of  the  liquid,  or  liquids,  and  plates  composing 
the  elements,  and  external  resistance,  i.  e.,  that  of  the  conducting 
system  outside  of  the  battery. 

Ohm's  Law. — This  fundamental  empirical  law  is  to  the  effect 
that:  The  current  strength  is  directly  proportionate  to  the  electro- 
motive force,  and  inversely  proportionate  to  the  resistance.  Or: 

TT  TT 

C=«,  and  consequently:  .R=Q-,  and  E=RC,  also. 

Electrolysis. — We  have  seen  (p.  18)  that  when  a  current  passes 
through  a  conductor  of  the  second  order  certain  constituents,  called 
ions,  are  separated  from  the  conductor.  This  occurs  with  all  liquids, 
whether  solutions  or  fused  solids,  which  are  conductors,  and  the 
process  is  called  electrolysis,  while  the  substance  acted  upon,  the 
conductor,  is  called  an  electrolyte.  The  ions  are  given  off,  one  at  each 
electrode,  and  entirely  unmixed  with  each  other.  Those  that  are 
given  off  at  the  positive  electrode,  or  anode,  being  attracted  thereby, 
are  charged  with  negative  electricity,  and  are  therefore  electronega- 
tive ions,  or  anions.  Those  which  are  given  off  at  the  negative 
electrode,  or  cathode,  are  electropositive  ions,  or  cations.  Thus, 
when  water  is  electrolyzed,  pure  hydrogen  is  given  off  at  the  negative 
electrode,  and  pure  oxygen  at  the  positive  electrode ;  and  when  hydro- 
chloric acid  solution  is  electrolyzed  pure  hydrogen  is  again  given 
off  at  the  negative  electrode,  and  pure  chlorine  gas  at  the  positive. 
(See  p.  33.) 


CHEMICAL  PHENOMENA  21 

Electrical  Units.  —  The  Ohm  is  the  unit  of  resistance.  It  is  the 
resistance  offered  by  a  column  of  mercury,  at  0°  C.,  106.3  cent,  long, 
weighing  14.4521  gm.,  and  having  a  uniform  cross-section  of  1  sq.  mm. 
The  Megohm,  for  the  measurement  of  high  resistances,  is  1,000,000 
ohms  ;  and  the  Microhm,  for  the  measurement  of  small  resistances,  is 


The  Ampere  is  the  unit  of  current  strength.  It  is  a  current 
which  will  deposit  4.025  gm.  of  metallic  silver  in  one  hour  from  a 
neutral  solution  of  silver  nitrate  (see  electrolysis).  A  milliampere 
is  ToVs-  ampere. 

The  Volt  is  the  unit  of  E.  M.  F.  It  is  that  E.  M.  F.  which,  acting 
steadily  through  a  conductor  having  a  resistance  of  one  ohm  will 
produce  a  current  of  one  ampere.  It  is  also  {£  Jf  the  E.  M.  F.  of  a 
standard  Clark's  cell  at  15°  C. 

The  Coulomb  is  the  unit  of  electrical  quantity.  It  is  the  quan- 
tity of  electricity  transferred  in  one  second  by  a  current  of  one 
ampere. 

The  Farad  is  the  unit  of  capacity.  It  is  the  capacity  of  a  con- 
denser charged  to  a  potential  of  one  volt  by  one  coulomb  of 
electricity. 

The  Watt  is  the  unit  of  energy.  It  represents  the  work  done 
by  one  ampere  with  a  pressure  of  one  volt.  One  watt  per  second 
is  equal  to  T}g  of  a  horse  power,  or  44.236  foot  pounds.  The 
kilowatt,  1000  watts,  is  the  unit  used  by  electrical  engineers. 

CHEMICAL  PHENOMENA. 

Elements.  —  Most  substances  may  be  so  decomposed  as  to  yield 
two  or  more  other  substances,  distinct  in  their  properties  from  the 
substance  from  whose  decomposition  they  resulted,  and  from  each 
other.  If,  for  example,  sugar  is  treated  with  sulphuric  acid,  it 
blackens,  and  a  mass  of  charcoal  separates.  Upon  further  examina- 
tion we  find  that  water  has  also  been  produced.  From  this  water 
we  may  obtain  two  gases,  differing  from  each  other  widely  in  their 
properties.  Sugar  is  therefore  made  up  of  carbon  and  the  two  gases, 
hydrogen  and  oxygen;  but  it  has  the  properties  of  sugar,  and  not 
those  of  either  of  its  constituent  parts.  There  is  no  method  known 
by  which  carbon,  hydrogen  and  oxygen  can  be  split  up,  as  sugar  is, 
into  other  dissimilar  substances. 

An  element  is  a  substance  which  cannot  by  any  known  means 
be  split  up  into  other  dissimilar  bodies. 

Elements  are  also  called  elementary  substances  or  simple  sub- 
stances. 

The  number  of  well-characterized  elements  at  present  known  is 
eighty-three  (list  p.  27,  see  also  p.  54).  Of  these  eighty-three  ele- 
ments comparatively  few  enter  into  the  composition  of  the  earth's 


22  TEXT-BOOK   OF   CHEMISTRY 

crust  (with  the  atmosphere  and  water),  and  about  ten  of  them  con- 
stitute approximately  97  or  98  per  cent,  of  the  whole.  These,  with 
the  approximate  proportions  of  each,  are : 

Oxygen    ...  50  per  cent.  Sodium  .      .  .2.5  per  cent. 

Silicon      .      .      .  25     "     "  Potassium     .  .2.5     "  " 

Aluminium   .      .     7    "     "  Magnesium  .  .2       "  ll 

Iron    .      .      .      .     4    "     il  Hydrogen     .  .   1 

Calcium         .      .     3     "     "  Titanium      .  .   0.5     "  " 

Total   .      .       97.5    "     " 

It  will  be  noticed  that  elements  which  are  of  great  importance  in 
their  relation  to  life  (such  as  carbon,  nitrogen,  phosphorus,  sulphur, 
and  chlorine)  and  such  valuable  and  useful  elements  as  gold,  silver, 
and  mercury, — all  combined  only  furnish  about  2.5  per  cent,  of  the 
total. 

The  elements  found  in  the  human  body  are  carbon,  hydrogen, 
oxygen,  nitrogen,  sulphur,  phosphorus,  fluorine,  chlorine,  iodine, 
silicon,  sodium,  potassium,  calcium,  magnesium,  lithium,  iron,  and 
occasionally  traces  of  manganese,  copper,  and  lead. 

Compounds  are  substances  made  up  of  two  or  more  elements 
chemically  united  with  each  other  in  definite  proportions.  Com- 
pounds exhibit  properties  of  their  own  which  differ  from  those  of 
the  constituent  elements  to  such  a  degree  that  the  properties  of  a 
compound  can  never  be  deduced  from  a  knowledge  of  those  of  the 
constituent  elements.  Common  salt,  for  instance,  is  composed  of 
39.4  per  cent,  of  the  light  bluish-white  metal,  sodium,  and  60.6  per 
cent,  of  the  greenish-yellow,  suffocating  gas,  chlorine. 

Compounds  made  up  of  two  elements  only  are  called  binary 
compounds;  those  consisting  of  three  elements,  ternary  compounds; 
those  containing  four  elements,  quaternary  compounds,  etc. 

A  mixture  is  composed  of  two  or  more  substances,  elements  or 
compounds,  mingled  in  any  proportion,  without  chemical  action 
between  the  constituents.  The  characters  of  a  mixture  may  be 
predicated  from  a  knowledge  of  the  properties  of  its  constituents. 
Thus  sugar  and  water  may  be  mixed  in  any  proportion,  and  the 
mixture  will  have  the  sweetness  of  the  sugar,  and  will  be  liquid 
or  solid,  according  as  the  liquid  or  solid  ingredient  predominates 
in  quantity. 

Laws  governing  the  combination  of  elements. — THE  LAW  OF 
DEFINITE  PROPORTIONS. — The  relative  weights  of  elementary  sub- 
stances in  a  compound  are  definite  and  invariable.  If,  for  example, 
we  analyze  water,  we  find  that  it  is  composed  of  eight  parts  by 
weight  of  oxygen  for  each  part  by  weight  of  hydrogen,  and  that 
this  proportion  exists  in  every  instance,  whatever  the  source  of  the 


CHEMICAL   PHENOMENA  23 

water.  If,  instead  of  decomposing,  or  analyzing  water,  we  start 
from  its  elements,  and  by  synthesis  cause  them  to  unite  to  form 
water,  we  find  that,  if  the  mixture  be  made  in  the  proportion  of 
eight  oxygen  to  one  hydrogen  by  weight,  the  entire  quantity  of  each 
gas  will  be  consumed  in  the  formation  of  water.  But  if  an  excess  of 
either  have  been  added  to  the  mixture,  that  excess  will  remain  after 
the  combination. 

THE  LAW  OF  MULTIPLE  PROPORTIONS. — When  two  elements  unite 
with  each  other  to  form  more  than  one  compound,  the  resulting 
compounds  contain  simple  multiple  proportions  of  one  element  as 
compared  with  a  constant  quantity  of  the  other. 

Oxygen  and  nitrogen,  for  example,  unite  with  each  other  to  form 
five  compounds.  In  these  the  two  elements  bear  to  each  other  the 
following  relations  by  weight: 

In  the  first,  14   parts  of  nitrogen  to  8  X  1  —    8  of  oxygen. 

In  the  second,  14  parts   of  nitrogen  to  8  X  2  =  16  of  oxygen. 

In  the  third,  14  parts  of  nitrogen   to  8  X  3  —  24  of  oxygen. 

In  the  fourth,  14  parts  of  nitrogen  to  8  X  4  =  32  of  oxygen. 

In  the  fifth,  14  parts  of  nitrogen   to  8  X  5  —  40  of  oxygen. 

THE  LAW  OF  RECIPROCAL  PROPORTIONS. — The  ponderable  quan- 
tities in  which  substances  unite  with  the  same  substance  express 
the  relation,  or  a  simple  multiple  thereof,  in  which  they  unite  with 
each  other.  For  example:  71  parts  of  chlorine  combine  with  40 
parts  of  calcium,  and  16  parts  of  oxygen  also  combine  with  40  parts 
of  calcium,  therefore  71  parts  of  chlorine  combine  with  16  parts  of 
oxygen,  or  the  two  elements  combine  in  the  proportion  of  some  simple 
multiples  of  71  and  16. 

Mixtures  of  solids  are  usually  mechanical  mixtures,  but  in  some 
instances  the  particles  of  solid  mixtures  are  so  intimately  inter- 
mingled that  the  products  are  referred  to  as  solid  solutions.  Indeed, 
when  one  constituent  predominates  largely,  there  is  reason  to  believe 
that  "dissociation"  may  occur,  as  in  dilute  liquid  solutions.  Iso- 
morphous  mixtures  are  crystals  obtained  by  evaporation  of  mixed 
solutions  of  isomorphous  compounds,  such  as  the  alums,  which  crys- 
tals contain  the  several  salts,  homogeneously  distributed  throughout, 
and  in  any  proportions.  Metallic  alloys,  glasses,  and  probably  dyed 
fibers  are  solid  solutions. 

For  liquid  solutions,  see  pp.  14,  15. 

Combination  of  gaseous  elements  by  volume. — The  laws  of 
definite  proportions,  of  multiple  proportions,  and  of  reciprocal  pro- 
portions (pp.  22,  23),  refer  to  proportions  by  weight  in  which  ele- 
ments unite  to  form  compounds. 

When  the  proportions  by  volume  in  which  gaseous  elements  com- 
bine to  form  compounds  are  compared  with  each  other  and  with  the 
volumes  of  the  gases  produced,  all  at  the  same  temperature  and  pres- 


24  TEXT-BOOK   OF   CHEMISTRY 

sure,  simple  relations  are  also  found  to  exist,  which  are  expressed  in 
the  laws  of  Gay-Lussac : 

First. — There  exists  a  simple  relation  between  the  volumes  of 
gases  which  combine  with  each  other. 

Second. — There  exists  a  simple  relation  between  the  sum  of 
the  volumes  of  the  constituent  gases,  and  the  volume  of  the  gas 
formed  by  their  union.  For  example  : 

1  volume  chlorine  unites  with  1  volume  hydrogen  to  form  2  volumes  hydrochloric 

acid. 
1  volume  oxygen  unites  with  2  volumes  hydrogen  to  form  2  volumes  vapor  of 

water. 

1  volume  nitrogen  unites  with  3  volumes  hydrogen  to  form  2  volumes  ammonia. 
1  volume  oxygen  unites  with  1  volume  nitrogen  to  form  2  volumes  nitric  oxide. 
1  volume  oxygen  unites  with  2  volumes  nitrogen  to  form  2  volumes  nitrous  oxide. 

It  will  be  noted  that  hydrogen  combines  with  chlorine,  oxygen  and 
nitrogen  in  the  respective  proportions  by  volume  of  1:1,  2:1  and 
3 : 1.  Also,  that,  while  the  volume  of  the  compound  of  hydrogen  and 
chlorine  is  equal  to  the  sum  of  the  volumes  of  the  components,  in  the 
formation  of  the  compound  with  oxygen  there  is  a  condensation  in 
volume  of  one-third,  and  of  that  with  nitrogen  of  one-half. 

Molecular  and  Atomic  Theories. — Postulate  of  Avogadro,  or  of 
Ampere. — In  explanation  of  the  facts  just  cited  (as  well  as  of  many 
others),  it  is  assumed  that  matter  is  not  infinitely  divisible,  that  there 
is  a  certain  smallest  quantity  of  cny  substance  which  can  exist  in  the 
free  state,  which  is  called  the  molecule.  With  regard  to  compound 
substances  (p.  22),  this  is  more  than  a  mere  assumption,  for,  con- 
sidering the  smallest  quantity  of  a  compound,  however  small  it  may 
be,  it  still  retains  the  properties  of  the  compound,  but  it  contains  at 
least  two  smaller  magnitudes,  of  substances  whose  properties  differ 
from  those  of  the  compound,  i.  e.,  those  of  the  elements  of  which  it 
is  composed,  and,  therefore,  it  cannot  itself  be  infinitely  small.  The 
molecule  of  hydrochloric  acid  contains  both  hydrogen  and  chlorine, 
and,  however  small  it  may  be,  the  whole  must  be  greater  than  either 
of  its  parts,  and  it  must  therefore  have  a  definite  magnitude. 

Almost  simultaneously,  in  1811  and  1812,  Avogadro  and  Ampere 
based  upon  the  facts  described  in  the  laws  of  Gay-Lussac  the  postu- 
late that  equal  volumes  of  gases,  under  like  conditions  of  tem- 
perature and  pressure,  contain  equal  numbers  of  molecules. 

This  is  usually  referred  to  as  the  "law"  of  Avogadro,  or  of 
Ampere.  It  has,  however,  not  the  force  of  a  scientific  "law,"  which, 
like  the  laws  above  quoted,  is  simply  a  generalized  statement  of  a 
series  of  observed  and  proven  facts.  This  statement,  being  based 
upon  the  undemonstrable  assumption  of  the  existence  of  molecules,  is 
no  more  capable  of  proof  than  is  the  postulate  of  Euclid,  that  "a 
straight  line  may  be  drawn  between  any  two  points. ' '  But  this  postu- 


CHEMICAL  PHENOMENA  25 

late  of  Avogadro  has  proven  itself  to  be  of  enormous  utility  in  the 
development  of  both  chemistry  and  physics ;  and  its  close  and  uniform 
accordance  with  the  results  of  both  physical  and  chemical  investiga- 
tions, and  with  the  modern  kinetic  theory  of  gases  lends  it  addi- 
tional support. 

Applying  the  postulate  of  Avogadro  to  the  laws  of  Gay-Lussac, 
we  may  translate  the  first  three  combinations  given  in  the  table  on 
page  24,  into  the  following: 

1  molecule  chlorine  unites  with  1  molecule  hydrogen,  to  form  2  mole- 
cules hydrochloric  acid. 

1  molecule  oxygen  unites  with  2  molecules  hydrogen,  to  form  2  mole- 
cules vapor  of  water. 

1  molecule  nitrogen  unites  with  3  molecules  hydrogen,  to  form  2 
molecules  ammonia. 

But  the  ponderable  quantities  in  which  these  combinations  take 
place  are: 

35.5   chlorine  to 1   hydrogen. 

16      oxygen  to 2   hydrogen. 

14       nitrogen    to 3    hydrogen. 

And  as  single  molecules  of  hydrogen,  oxygen  and  nitrogen  are  in 
these  combinations  subdivided  to  form  2  molecules  of  hydrochloric 
acid,  water  and  ammonia,  it  follows  that  these  molecules  must  each 
contain  two  equal  quantities  of  hydrogen,  oxygen  and  nitrogen,  less 
in  size  than  the  molecules  themselves.  And,  further,  as  in  these 
instances  each  molecule  contains  two  of  the  smaller  quantities,  or 
atoms,  the  relation  between  the  weights  of  the  molecules  must  also 
be  the  relation  between  the  weights  of  the  atoms,  and  we  may  there- 
fore express  the  combinations  thus: 

1  atom  chlorine  weighing  35.5  unites  with  1  atom  hydrogen  weighing  1 ; 
1  atom  nitrogen  weighing  16  unites  with  2  atoms  hydrogen  weighing  2; 
1  atom  oxygen  weighing  14  unites  with  3  atoms  hydrogen  weighing  3; 

and  consequently,  if  the  atom  of  hydrogen  weighs  1,  that  of  chlorine 
weighs  35.5,  that  of  oxygen  16,  and  that  of  nitrogen  14. 

Assuming,  then,  the  existence  of  molecules  and  atoms,  the  distinc- 
tion between  them  may  be  expressed  in  the  following  definitions: 

A  molecule  is  the  smallest  quantity  of  any  substance  that  can 
exist  in  the  free  state. 

An  atom  is  the  smallest  quantity  of  an  elementary  substance 
that  can  enter  into  a  chemical  reaction. 

The  molecule  is  always  made  up  of  atoms,  upon  whose  nature, 
number  and  arrangement  with  regard  to  each  other,  the  properties  of 
the  substance  depend.  In  an  elementary  substance  the  atoms  compos- 


26  TEXT-BOOK   OF   CHEMISTRY 

ing  the  molecules  are  the  same  in  kind,  and  usually  two  in  number. 
In  compound  substances  they  are  dissimilar,  and  vary  in  quantity 
from  two  in  a  simple  compound,  like  hydrochloric  acid,  to  hundreds 
or  thousands  in  more  complex  substances. 

The  word  atom  can  only  be  used  in  speaking  of  an  elementary 
body,  and  that  only  while  it  is  passing  through  a  reaction.  When 
liberated,  atoms  usually  unite  to  form  other  molecules,  although 
there  are  a  few  elements  whose  molecules  consist  of  single  atoms. 

The  term  molecule  applies  indifferently  to  elements  and  com- 
pounds. 

Atomic  Weight. — The  atoms  of  the  several  elements  have  definite 
relative  weights;  and  upon  the  accurate  determination  of  these  all 
methods  of  quantitative  chemical  analysis  depend.  (See  Stoichiome- 
try,  p.  41.)  Clearly,  as  the  atomic  weights  are  relative,  the  weight  of 
one  atom  of  any  element  may  be  selected  as  the  unit  or  base  in  terms  of 
which  the  weights  of  the  atoms  of  other  elements  may  be  expressed. 
Formerly  the  unit  adopted  was  the  weight  of  one  atom  of  the  lightest 
known  substance,  hydrogen,  and  the  atomic  weight  of  an  element 
represented  the  weight  of  one  atom  of  that  element  as  compared 
with  the  weight  of  one  atom  of  hydrogen.  What  the  absolute 
weight  of  an  atom  of  any  element  may  be  we  do  not  know. 

But  the  determination  of  the  atomic  weight  of  an  element  depends 
upon  accurate  analyses  of  compounds  of  that  element,  and  hydrogen, 
unfortunately,  forms  compounds  amenable  to  accurate  analysis  with 
but  few  other  elements.  Oxygen,  on  the  other  hand,  forms  compounds 
with  a  great  number  of  other  elements,  and  determinations  of  atomic 
weights  have  usually  been  made  with  reference  to  oxygen  in  the  first 
instance.  If  expressed  in  terms  of  H  =  1,  therefore,  their  accuracy 
depends  upon  the  correctness  of  the  determination  of  the  ratio  be- 
tween the  atomic  weights  of  oxygen  and  of  hydrogen,  which,  accord- 
ing to  the  most  recent  determination,  is  H  :  0  : :  1 : 15.88  or  0  :  H  : :  16 : 
1.008.  But  this  ratio  cannot  be  considered  as  being  definitely  de- 
cided ;  therefore,  to  avoid  the  necessity  of  a  recalculation  of  all  atomic 
weights  with  increased  accuracy  of  the  determination  of  the  ratio 
0 :  H,  chemists  have  agreed  that  the  atomic  weight  of  oxygen  be  taken 
as  the  base  of  the  system  at  16.  The  following  table  contains  a  list 
of  the  elements  at  present  known,  with  their  atomic  weights,  calcu- 
lated with  0  =  16  (known  as  the  International  Atomic  Weights).  It 
is  recommended  that  students  use  the  nearest  integral  numbers: 
c.  g.,  108  for  silver ;  1  for  hydrogen. 

Molecular  Weight. — We  have  seen  (p.  25)  that  in  the  formation 
of  hydrochloric  acid,  water,  and  ammonia,  the  molecules  of  hydrogen 
each  contribute  one-half  of  their  material  to  the  formation  of  each  of 
the  several  new  molecules.  The  molecules  of  hydrogen  must,  there- 
fore, contain  at  least  two  atoms  each;  and  it  can  also  be  shown  that 
the  molecules  of  chlorine,  oxygen,  nitrogen  and,  in  fact,  of  most 


ELEMENTS 


27 


ELEMENTS 


NAME 

J 

B 
>> 

in 

Atomic  Weight 

NAME 

1 

(S 

c/3 

Atomic  Weight 

0* 

ll 
<" 

Interna- 
tional 
(1918) 
O=i6 

%2 

§3 

<~ 

Interna- 
tional 
(1918) 
O=i6 

96.0 
144.3 
20.2 
58.68 

222.4 
14.01 
190.9 
16.00 
106.7 
31.04 
195.2 

39.10 
140.9 
226.0 
102.9 
85.45 
101.7 
150.4 
44.1 
79.2 
28.3 
107.88 
23.00 
87.63 
32.06 
181.5 
127.5 
159.2 
204.0 
232.4 
168.5 
118.7 
48.1 

184.0 
238.2 
51.0 
130.2 
173.5 
88.7 
65.37 
90.6 

Aluminium   

Al 

Sb 
A 
As 
Ba 
Bi 
B 
Br 
Cd 
Cs 
Ca 
C 
Ce 
Cl 
Cr 
Co 
Cb 
Cu 
Dy 

Er 
Eu 
F 
Gd 
Ga 
Ge 
Gl 
Au 
He 
Ho 
H 
In 
I 
Ir 
Fe 
Kr 
La 
Pb 
Li 
Lu 
Mg 
Mn 

Hg 

27 

120 
40 
75 
137 
208 
11 
80 
112 
133 
40 
12 
140 
35.5 
52 
59 
93 
63 
162 
168 
152 
19 
157 
70 
72 
9 
197 
4 
163 
1 
115 
127 
193 
56 
83 
139 
207 

175 
24 
55 

200 

27.1 

120.2 
39.88 
74.96 
137.37 
208.00 
11.0 
79.92 
112.40 
132.81 
40.07 
12.005 
140.25 
35.46 
52.0 
58.97 
93.1 
63.57 
162.5 
167.7 
152.0 
19.0 
157.3 
69.9 
72.5 
9.1 
197.2 
4.00 
163.5 
1.008 
114.8 
126.92 
193.1 
55.84 
82.92 
139.0 
207.20 
6.94 
175.0 
24.32 
54.93 

200.6 

Molybdenum  
Neodymium     
Neon  .  .  . 

Mv 

Nu 

No 
Ni 

Nt 
N 
Os 
0 
Pd 
P 
Pt 

K 
Pr 
Ra 
Rh 
Rb 
Ru 
Sa 
Sc 
Se 
Si 
Ag 
Na 
Sr 
S 
Ta 
Te 
Tb 
Tl 
Th 
Tm 
Sn 
Ti 

W 
U 
V 
Xe 
Yb 
Yt 
Zn 
Zr 

96 
144 
20 
58 

222 
14 
L91 
16 
107 
31 
195 

39 
141 
226 
103 
85 
102 
150 
44 
79 
28 
108 
23 
87.5 
32 
181 
127 
159 
204 
232 
168 
118.5 
48 

184 
238 
51 
130 
173 
89 
65 
90 

Antimony 
(Stibium)    
Argon     

Nickel    . 

Arsenic    . 

Niton   (Radium 
Emanation  )     ... 
Nitrogen 

Barium    . 

Bismuth  

Boron   

Osmium 

Bromine    .  .  . 

Oxygen  
Palladium    

Cadmium   
Caesium    
Calcium    

Phosphorus     .  .  . 

Platinum 

Carbon   

Potassium 

Cerium    

(  Kalium  ) 

Chlorine    .    . 

Praseodymium   (c) 
Radium 

Chromium   

Cobalt    

Rhodium 

Columbium  (a)  .  .  . 
Copper    (  Cuprum  ) 
Dysprosium    
Erbium    

Rubidium    

Ruthenium 

Samarium   

Scandium 

Europium    

Selenium    . 

Fluorine 

Silicon    
Silver  (Argentum) 
Sodium  (Natrium) 
Strontium 

Gadolinium     

Gallium 

Germanium   

Glucinum    (  6  )    ... 
Gold    (Aurum)    .. 
Helium    .    . 

Sulphur    .... 

Tantalum    
Tellurium    
Terbium    
Thallium    .... 

Holmium    . 

Hydrogen     

Indium    

Thorium    .... 

Iodine  

Thulium 

Iridium    .  . 

Tin  (  Stannum  )  .  .  . 
Titanium 

Iron    (  Ferrum  )    .  . 
Krypton 

Tungsten 
(Wolframium)  . 
Uranium 

Lanthanum   
Lead  (Plumbum)   , 
Lithium  .  . 

Vanadium 

Lutecium   
Magnesium    
Manganese    
Mercury 
(Hydrargyrum) 

Xenon     

Ytterbium    (d) 
Yttrium  

Zinc    

Zirconium   

(a)   Also  formerly  known  as  Niobium,  Nb. 
(&)   Also  formerly  known  as  Beryllium,   Be. 

(c)  Also  formerly  known  as  Didymium,  Di. 

(d)  Also  known  as  Neoytterbium. 


28  TEXT-BOOK   OF   CHEMISTRY 

other  elements  also  contain  at  least  two  atoms  each.  There  are  excep- 
tions, however,  in  the  cases  of  several  metals,  whose  molecules  con- 
sist of  single  atoms. 

Taking  the  weight  of  one  atom  of  hydrogen  as  the  basis  of  mo- 
lecular as  well  as  of  atomic  weights  the  molecular  weight  of  a 
substance  is  the  weight  of  its  molecule  as  compared  with  the  weight 
of  an  atom  of  hydrogen.  It  is  immaterial  to  this  definition  what  the 
absolute  weight  of  the  hydrogen  atom  may  be,  or  whether  it  is  con- 
sidered as  weighing  1.000  or  1.008.  The  molecular  weight  is  also, 
obviously,  the  sum  of  the  weights  of  the  atoms  making  up  the 
molecule. 

A  ready  method  for  determining  the  molecular  weights  of  sub- 
stances existing  or  obtainable  in  the  aeriform  state  is  based  upon  the 
postulate  of  Avogadro.  The  specific  gravity  of  a  gas  or  vapor  re- 
ferred to  hydrogen  is  the  weight  of  any  given  volume  as  compared 
with  the  weight  of  an  equal  volume  of  hydrogen  (p.  3).  But  equal 
volumes  contain  equal  numbers  of  molecules  (p.  24),  and  the  relation 
of  weights,  the  sp.  gr.,  of  the  whole  is  the  same  for  any  equal  frac- 
tions, down  to  the  molecules,  and  therefore  this  specific  gravity  is  the 
weight  of  a  molecule  of  the  gas  as  compared  with  that  of  a  molecule 
of  hydrogen;  and  as  the  molecule  of  hydrogen  contains  two  atoms, 
while  one  atom  is  the  unit  of  comparison,  it  follows  that  the  specific 
gravity  of  a  gas  compared  with  hydrogen,  multiplied  by  two,  is  its 
molecular  weight. 

For  example,  the  gas  acetylene  and  the  liquid  benzene  each  con- 
tain 92.31  per  cent,  of  carbon,  and  7.69  per  cent,  of  hydrogen ;  which 
is  equivalent  to  24  parts,  or  two  atoms  of  carbon;  and  2  parts,  or 
two  atoms  of  hydrogen.  The  sp.  gr.  of  acetylene,  referred  to  hydro- 
gen =  2,  is  13 ;  its  molecular  weight  is,  therefore,  26,  and  its  molecule 
contains  two  atoms  of  carbon  and  two  atoms  of  hydrogen.  The  sp. 
gr.  of  vapor  of  benzene  is  39;  its  molecular  weight  is,  therefore,  78, 
and  its  molecule  contains  six  atoms  of  carbon  and  six  atoms  of 
hydrogen. 

When  a  substance  is  not  capable  of  being  volatilized,  its  molecular 
weight  may  be  obtained  from  certain  properties  of  its  solutions,  which 
will  bo  considered  in  connection  with  organic  chemistry  (see  p.  195). 

The  vapor  densities  of  comparatively  few  elements  are  known: 

Vapor  Atomic          Molecular 

Density  Weight  Weight 

Hydrogen    1                    1 

Oxygen    16  16  32 

Sulphur     32  32  64 

Selenium 82  79  164 

Tellurium    130  128  260 

Chlorine 35.5  35.5  71 

Bromine  80  80  160 

Iodine  .         127  127  254 


VALENCE  29 

Vapor  Atomic  Mole'cular 

Density  Weight  Weight 

Phosphorus    63  31  124 

Arsenic    150  75  300 

Nitrogen 14  14  28 

Potassium    39  39  78 

Cadmium    56  112  112 

Mercury    100  200  200 

The  atomic  weight  being,  in  most  of  the  above  instances,  equal 
to  the  vapor  density,  and  to  half  the  molecular  weight,  it  may  be 
inferred  that  tlie  molecules  of  these  elements  consist  of  two  atoms. 
Noticeable  discrepancies  exist  in  the  case  of  four  elements.  The 
molecular  weights  of  phosphorus  and  arsenic,  as  obtained  from  their 
vapor  densities,  are  not  double,  but  four  times  as  great  as  their 
atomic  weights.  The  molecules  of  phosphorus  and  arsenic  are,  there- 
fore, supposed  to  contain  four  atoms.  Those  of  cadmium,  zinc  and 
mercury  contain  but  one  atom. 

Gram-molecule — Mol. — That  quantity  of  a  substance  whose 
weight  is  represented  by  its  molecular  weight  expressed  in  grams  is 
called  a  gram-molecule,  or  mol;  as  32  gms.  oxygen,  70.9  gms. 
chlorine,  18.016  gms.  water. 

The  mol  is  a  quantity  both  theoretically  and  practically  important. 
We  have  now  to  consider  it  in  connection  with  certain  facts  already 
referred  to. 

Molecular  Volume. — The  molecular  volume  of  a  gas  or  liquid 
is  the  volume  occupied  by  one  'mol  of  the  substance  under  normal 
conditions. 

According  to  the  postulate  of  Avogadro  (p.  24),  equal  molecular 
weights  (mols)  of  all  gases  must  occupy  the  same  volume,  at  the 
same  temperature  and  pressure,  or,  in  other  words:  the  molecular 
volume  (Vm)  of  gases  is  a  constant  quantity.  The  molecular  volume 
of  a  gas  is  the  product  of  its  specific  volume  (Vs),  i.e.,  the  vol- 
ume in  cc.  which  1  gm.  occupies  at  0°  and  76  cm.,  and  its  molecular 
weight.  Thus 

Weight  of  1  L  in  gms. 

at  0°  and  76  cm.  Vs.  Mw.  VsxMw,  in  L. 

Hydrogen     0.08988 11,111     2.016 22.399 

Oxygen     1.4291    699.7 32.000 22.390 

Nitrogen    1.2507   799.5 28.080 22.450 

The  volume  occupied  by  1  mol  of  a  gas  at  0°  and  76  cm.  is  22.4 
liters.  Consequently  the  weight,  p,  of  any  given  volume  of  gas,  v,  in 

liters,  reduced  to  normal  conditions  is:  p=  *'  ^2*V  >  and  tne  volume, 

22  4  T) 

in  liters,  of  any  given  weight  of  gas  is:  v="T'      - 

JVJL\V. 

Valence  or  atomicity. — It  is  known  that  the  atoms  of  different 
elements  possess  different  capacities  for  combining  with  and  for  re- 
placing atoms  of  hydrogen.  Thus: 


30  TEXT-BOOK   OF   CHEMISTRY 

1  atom  of  chlorine  combines  with  1  atom  of  hydrogen. 
1  atom  of  oxygen  combines  with  2  atoms  of  hydrogen. 
1  atom  of  nitrogen  combines  with  3  atoms  of  hydrogen. 
1  atom  of  carbon  combines  with  4  atomc  of  hydrogen. 

The  valence,  atomicity,  or  equivalence  of  an  element  is  the 
saturating  capacity  of  one  of  its  atoms  as  compared  with  that  of 
one  atom  of  hydrogen. 

Elements  may  be  classified  according  to  their  valence  into— 

Univalent  elements,  or  monads ".  . Cl' 

Bivalent  elements,   or   dyads 0" 

Trivalent   elements,   or   triads B"' 

Quadrivalent  elements,  or  tetrads Civ 

Quinquivalent   elements,    or    pentads Pv 

Sexivalent   elements,    or    hexads W™ 

Elements  of  even  valence,  i.  e.,  those  which  are  bivalent,  quad- 
rivalent, or  sexivalent,  are  sometimes  called  artiads;  those  of  uneven 
valence  being  designated  as  perissads. 

In  notation  the  valence  is  indicated,  as  above,  by  signs  placed 
to  the  right  and  above  the  symbol  of  the  element. 

But  the  valence  of  the  elements  is  not  fixed  and  invariable. 
Thus,  while  chlorine  and  iodine  each  combine  with  hydrogen,  atom 
for  atom,  and  in  those  compounds  are  consequently  univalent,  they 
unite  with  each  other  to  form  two  compounds — one  containing  one 
atom  of  iodine  and  one  of  chlorine,  the  other  containing  one  atom  of 
iodine  and  three  of  chlorine.  Chlorine  being  univalent,  iodine  is 
obviously  trivalent  in  the  second  of  these  compounds.  Again,  phos- 
phorus forms  two  chlorides,  one  containing  three,  the  other  five 
atoms  of  chlorine  to  one  of  phosphorus. 

In  view  of  these  facts,  we  must  consider  either:  1,  That  the 
valence  of  an  element  is  that  which  it  exhibits  in  its  most  saturated 
compounds,  as  phosphorus  in  the  pentachloride,  and  that  the  lower 
compounds  are  non-saturated,  and  have  free  valences;  or  2,  that 
the  valence  is  variable.  The  first  supposition  depends  too  much 
upon  the  chances  of  discovery  of  compounds  in  which  the  element 
has  a  higher  valence  than  that  which  might  be  considered  the  max- 
imum to-day.  The  second  supposition — notwithstanding  the  fact 
that,  if  we  admit  the  possibility  of  two  distinct  valences,  we  must 
also  admit  the  possibility  of  others — is  certainly  the  more  tenable 
and  the  more  natural.  In  speaking,  therefore,  of  the  valence  of  an 
element,  we  must  not  consider  it  as  an  absolute  quality  of  its  atoms, 
but  simply  as  their  combining  capacity  in  the  particular  class  of  com- 
pounds under  consideration.  Indeed,  compounds  are  known  in  whose 
molecules  the  atoms  of  one  clement  exhibit  two  distinct  valences. 
Thus,  ammonium  cyanate  (H4==N — 0 — C  =  N)  contains  two  atoms 
of  nitrogen :  one  in  the  ammonium  group  is  quinquivalent,  one  in  the 
acid  radical  is  trivalent. 


SYMBOLS 


31 


TABLE  OF  THE  VALENCES  OF  SOME  OF  THE  COMMONER  ELEMENTS 
AND  RADICALS. 


Uiiivalent 

Bivalent 

Trivalent 

Quadrivalent 

Quinquivalent 

Sexivalent 

H 
F 
Cl 
Br 
I 
Li 
Na 
K 
Ag 
Cu    (ous) 
Hg    (ous) 

0 
S 
Mn  (ous) 
Fe  (ous) 
Pb 
Sn  (ous) 
Ca 
Ba 
Mg 
Zn 
Cu    (ic) 
Hg   (ic) 

N 
P 
As 
Sb 
B 
Fe   (ic) 
Bi 
Al 

c 

Si 
S 
Pt 
Sn    (ic) 

N 
P 
As 
Sb 

S 

w 

(P04) 

(OH) 
(NO,) 

(NH4) 
(CN) 
(C2H302) 

(S04) 
(CO.) 

The  chemical  equivalent,  or  equivalent  weight,  of  an  element 
is  the  weight  of  that  element  capable  of  combining  with  unit  weight 
of  hydrogen  (or  chlorine).  It  is,  therefore,  its  atomic  weight  divided 
by  its  valence.  We  have  seen  (p.  25)  that  35.5  parts  by  weight  of 
chlorine  combine  with  1  part  by  weight  of  hydrogen,  16  of  oxygen 
with  2  of  hydrogen,  and  14  of  nitrogen  with  3  of  hydrogen. 
Chlorine  being  univalent,  oxygen  bivalent  and  nitrogen  trivalent, 
their  equivalent  weights  are,  therefore,  respectively:  35.5-f-l=:35.5, 
16-^-2=8,  and  14-^3=4.67.  (See  also  p.  37.) 

A  gram-equivalent  of  an  element  is  a  quantity  of  that  element 
whose  weight  in  grams  is  equal  to  its  molecular  weight  divided  by 
its  valence.  Thus  23  gms.  of  sodium,  and  65.4-T-2=32.7  gins,  of 
zinc,  are  gram  equivalents  of  those  metals. 

Symbols,  Formulae,  Equations. — Symbols  are  conventional 
abbreviations  of  the  names  of  the  elements ;  they  consist  of  the  initial 
letter  of  the  Latin  name  of  the  element,  to  which  is  usually  added 
one  of  the  other  letters.  If  there  are  more  than  two  elements  whose 
names  begin  with  the  same  letter,  the  single-letter  symbol  is  reserved 
for  the  commonest  element.  Thus,  we  have  ten  elements  whose  names 
begin  with  C;  of  these  the  commonest  is  Carbon,  whose  symbol  is 
C ;  the  others  have  double-letter  symbols,  as  Chlorine,  Cl ;  Cobalt,  Co ; 
Copper,  Cu  (Cuprum),  etc. 

These  symbols  do  not  indicate  simply  an  indeterminate  quan- 
tity, but  represent  one  atom  of  the  corresponding  element. 

When  more  than  one  atom  is  spoken  of,  the  number  of  atoms 
which  it  is  desired  to  indicate  is  written  either  before  the  symbol 
or,  in  small  figures,  after  and  below  it.  Thus,  H  indicates  one 


32  TEXT-BOOK   OF   CHEMISTRY 

atom  of  hydrogen;  2C1,  two  atoms  of  chlorine;  C4,  four  atoms  of 
carbon,  etc. 

What  the  symbol  is  to  the  element,  the  formula  is  to  the  com- 
pound. By  it  the  number  and  kind  of  atoms  of  which  the  molecule 
of  a  substance  is  made  up  are  indicated.  The  simplest  kind  of 
formula;  are  what  are  known  as  empirical  formulae,  which  indicate 
only  the  kind  and  number  of  atoms  which  form  the  compound.  Thus, 
HC1  indicates  a  molecule  composed  of  one  atom  of  hydrogen  united 
with  one  atom  of  chlorine;  5H20,  five  molecules,  each  composed  of 
two  atoms  of  hydrogen  and  one  atom  of  oxygen,  the  number  of 
molecules  being  indicated  by  the  proper  numeral  placed  before  the 
formula,  in  which  place  it  applies  to  all  the  symbols  following  it. 
Sometimes  it  is  desired  that  a  numeral  shall  apply  to  a  part  of  the 
symbols  only,  in  which  case  they  are  enclosed  in  parentheses;  thus, 
A12(S04)3  means  twice  Al  and  three  times  S04. 

For  other  varieties  of  formula?,  see  pp.  47,  48. 

Equations  are  combinations  of  formulae  and  algebraic  signs  so 
arranged  as  to  indicate  a  chemical  reaction  and  its  results.  The  signs 
used  are  the  plus  and  equality  signs ;  the  former  being  equivalent  to 
"and,"  and  the  second  meaning  "have  reacted  upon  each  other  and 
have  produced."  The  substances  entering  into  the  reaction  are 
placed  before  the  equality  sign,  and  the  products  of  the  reaction  after 
it ;  thus,  the  equation 

2KOH+H2S04=K2S04+2H20 

means,  when  translated  into  ordinary  language:  two  molecules  of 
potassium  hydroxide,  each  composed  of  one  atom  of  potassium,  one 
atom  of  hydrogen,  and  one  atom  of  oxygen,  and  one  molecule  of 
sulphuric  acid,  composed  of  two  atoms  of  hydrogen,  one  atom  of 
sulphur,  and  four  atoms  of  oxygen,  have  reacted  upon  eacli  other  and 
have  produced  one  molecule  of  potassium  sulphate,  composed  of  two 
atoms  of  potassium,  one  atom  of  sulphur,  and  four  atoms  of  oxygen, 
and  two  molecules  of  water,  each  composed  of  two  atoms  of  hydrogen 
and  one  atom  of  oxygen. 

As  no  material  is  ever  lost  or  created  in  a  reaction,  the  number 
of  each  kind  of  atom  occurring  before  the  equality  sign  in  an 
equation  must  always  be  the  same  as  that  occurring  after  it.  In 
writing  equations,  they  should  always  be  proved  by  examining 
whether  the  half  of  the  equation  before  the  equality  sign  contains 
the  same  number  of  each  kind  of  atom  as  that  after  the  equality 
sign.  If  it  does  not,  the  equation  is  incorrect. 

The  word  reaction  is  used  in  chemistry  with  two  distinct  mean- 
ings: As  applying  to  the  action  mentioned  above,  it  refers  to  the 
mutual  action  of  two  substances  upon  each  other.  In  the  other 
meaning  it  refers  to  the  action  of  substances  upon  certain  organic 
pigments.  Thus,  the  reaction  of  a  substance  is  acid,  when  it  turns 


ELECTROLYSIS  33 

blue   litmus   red;   alkaline,   when   it   turns   reddened   litmus   blue; 
amphoteric,  when  it  turns  red  litmus  blue  and  blue  litmus  red;  and 
neutral,  when  it  has  no  action  upon  either  blue  or  red  litmus. 
Chemical  reactions  in  the  former  sense  are  either: 

1.  Combinations,   also   called   syntheses,   in   which   elements   or 
simpler  compounds  unite  to  form  more  complex  molecules,  as  when 

2H2+02  =  H20 

2.  Decompositions,  also  called  analyses,  processes  the  reverse  of 
combinations,  as  when 

2H20=2H2+02;   and 

3.  Double  decompositions,  or  matatheses,  when  two  substances 
mutually  react  upon  each  other  with  formation  of  new  substances, 
as  when 

2KOH+H2S04=K2S04+2H20 

When  one  of  the  reagents  in  a  double  decomposition  is  water,  the 
process  is  called  hydrolysis  (see  p.  64). 

Special  varieties  of  these  several  kinds  of  reaction,  which  are 
sufficiently  distinctive,  have  received  distinguishing  names,  such  as 
condensations,  etc.,  and  will  be  considered  later.  There  also  occur, 
notably  with  the  compounds  of  carbon,  instances  of 

(4)  Atomic  rearrangement,  or  transposition,  in  which  the  com- 
position remains  the  same,  but  the  constitution  (p.  46)  is  changed: 
as  when  ammonium  isocyanate,  0  :C  :N.NH4  is  converted  into  urea, 
H2.NCO.NH2. 

Electrolysis. — We  have  seen  (p.  20)  that  when  hydrochloric  acid 
is  electrolyzed,  hydrogen  is  given  off  at  the  negative  pole,  and  is 
therefore  electropositive,  while  chlorine  is  given  off  at  the  positive 
pole,  and  is  therefore  electronegative.  But  if  a  compound  of  chlorine 
and  sulphur  is  electrolyzed,  chlorine  is  given  off  at  the  negative  elec- 
trode, and  is  therefore  electropositive.  Chlorine  is  consequently  elec- 
tropositive to  sulphur,  and  electronegative  to  hydrogen. 

The  results  of  electrolysis  of  binary  compounds  of  many  elements 
have  shown  that  oxygen  is  electronegative,  and  the  alkali  metals  (p. 
149)  are  electropositive  to  all  other  elements  with  which  they  form 
binary  compounds.  If  the  elements  are  arranged  in  an  electro- 
chemical series,  with  oxygen  at  the  electronegative  end  and  caesium 
at  the  electropositive  end,  and  if  the  other  elements  are  placed  in  the 
series  in  such  positions  that  each  will  be  between  oxygen  and  all 
other  elements  toward  which  it  is  electronegative,  it  will  be  found 
that  hydrogen  will  occupy  a  position  about  midway  between  the  two 
ends,  but  nearer  to  the  electronegative,  and  that  the  elements  of 
the  acidulous  class  (p.  52)  will  be  placed  between  hydrogen  and 
oxygen,  while  the  metals  will  be  placed  to  the  electropositive  side  of 


34  TEXT-BOOK   OF   CHEMISTRY 

hydrogen.     See  the  accompanying  arrangement  in  the  shape  of  a 
horseshoe. 


ELECTRONEGATIVE 

ELECTBOPOSITP 

Oxygen 
Sulphur 

Caesium 
Rubidium 

Nitrogen 

Potassium 

Fluorine 

Sodium 

Chlorine 

Lithium 

Bromine 

Barium 

Iodine 

Strontium 

Selenium 

Calcium 

Phosphorus 

Magnesium 

Arsenic 

Beryllium 

Chromium 

Yttrium 

Vanadium 

Erbium 

Molybdenum 

Aluminium 

Tungsten 

Zirconium 

Boron 

Thorium 

Carbon 

Cerium 

Antimony 

Didymium 

Tellurium 

Lanthanum 

Tantalum 

Manganese 

Columbium 

Zinc 

Titanium 

Iron 

Silicon 

Nickel 

Hydrogen 

Cobalt 

Gold 

Thallium 

Osmium 

Cadmium 

Iridium 

Lead 

Platinum 

Indium 

Rhodium 

Tin 

Ruthenium 

Bismuth 

Palladium 

Uranium 

Mercury 

Copper 

Silver" 

Arbitrarily,  elements  electronegative  to  hydrogen  are  con- 
sidered as  electronegative  elements,  those  electropositive  to  hydro- 
gen as  electropositive  elements. 

A  similar  separation  takes  place  in  the  electrolysis  of  compounds 
containing  more  than  two  elements,  one  element  being  liberated  at 
one  pole  and  the  remaining  group  of  elements  separating  at  the 
other.  This  primary  decomposition  is  generally  modified,  as  to  its 
final  products,  by  subsequent  chemical  reactions,  called  secondary 
actions.  When,  for  example,  a  solution  of  potassium  sulphate  is  elec- 
trolyzed,  the  liquid  surrounding  the  positive  electrode  becomes  acid 
in  reaction,  and  gives  off  oxygen.  At  the  same  time  the  liquid  at  the 
negative  side  becomes  alkaline,  and  gives  off  a  volume  of  hydrogen 
double  that  of  the  oxygen  liberated.  In  the  first  place  potassium 
sulphate,  which  consists  of  potassium,  sulphur  and  oxygen,  yields  on 
primary  separation  electropositive  potassium,  which  separates  at  the 
negative  pole;  and,  an  electronegative  group  of  sulphur  and  oxygen, 
which  goes  to  the  positive  pole : 

2K2S04=2Ka+2S04 


ELECTROLYSIS  35 

The  pcftassium  liberated  immediately  decomposes  the  surround- 
ing water,  forming  caustic  potash,  to  which  the  alkaline  reaction  is 
due,  and  hydrogen,  which  is  liberated: 

2K2+4H20=4KOH+2H2 

The  sulphur-oxygen  group  at  the  positive  pole  also  immediately 
reacts  with  water  to  form  sulphuric  acid,  and  oxygen  is  liberated: 
2S04+2H20=2H2S04+02 

one  molecule  of  oxygen  being  liberated  for  every  two  of  hydrogen. 

The  name  ion  was  first  applied  by  Faraday  to  the  primary 
products  of  electrolysis;  and  those  which  separate  at  the  positive 
electrode,  or  anode,  are  called  anions,  while  those  which  separate  at 
the  negative  electrode,  or  cathode,  are  called  cations.  Thus,  potas- 
sium sulphate  yields  the  cation  K,  and  the  anion  S04.  Cations  are 
designated  by  the  plus  sign,  anions  by  the  minus  sign.  Thus: 

+  +     — 
K2S04=K  K-f-S04,  or,  better,  the  cations,  as  well  as  their  valences, 

are  designated  by  the  proper  number  of  dots  placed  after  the  symbol, 
thus,  H",  Ca"  and  the  anions  similarly  by  prime  marks,  thus,  OH', 
S04",  and  As04"'.  Hydrogen,  the  metals,  and  basic  radicals  are 
cations;  Jiydroxyl  and  the  acid  residues  are  anions.  The  residues  of 
acids  are  compound  ions,  that  is,  ions  consisting  of  more  than  one 
element. 

According  to  the  earlier  views  of  electrolysis,  the  decomposition 
of  the  molecule  into  its  ions  was  considered  to  be  a  result  of  the 
action  of  the  galvanic  current.  According  to  the  theory  of  Arrhenius, 
dissociation  into  ions,  or  ionization,  occurs  when  the  electrolyte  is 
dissolved.  A  solution  of  potassium  chloride  contains  not  only  the 
molecular  KC1,  but  also  the  cation  K*  and  the  anion  Cl',  and  the 
action  of  the  current  is  to  separate  these,  already  liberated,  ions  at  the 
respective  electrodes.  It  is  assumed  that  the  hydrogen  and  metallic 
ions  are  charged  with  positive  electricity,  and  the  hydroxyl  and 
acid-residue  ions  with  negative  electricity,  and  therefore  the  former 
are  attracted  to  the  negatively  charged  cathode,  and  the  latter  to  the 
positively  charged  anode. 

We  have  seen  that  when  an  aqueous  solution  of  an  acid  is  elee- 
trolyzed,  hydrogen  is  always  given  off  at  the  cathode.  Although  hy- 
drogen exists  in  innumerable  compounds  other  than  acids,  it  is  only 
from  them  that  it  is  so  separated,  and  only  from  them  when  in 
solution.  That  this  hydrogen  does  not  originate  from  the  water  is 
shown  by  the  fact  that  perfectly  pure  water  is  neither  a  conductor 
nor  an  electrolyte.  It  is  only  in  solutions  of  acids  (or  in  solutions 
of  acid  salts  or  esters,  which  still  retain  acid  properties),  therefore, 
that  hydrogen  exists  in  the  ionized  form,  hydrion.  Hydrion  also  dif- 
fers from  molecular  or  atomic  hydrogen  in  other  respects.  It  is  only 
known  in  solution,  while  molecular  hydrogen  is  almost  insoluble  in 


36  TEXT-BOOK   OF   CHEMISTRY 

water.  It  reddens  litmus  and  is  replaceable  by  metals,  properties 
not  possessed  by  either  atomic  or  molecular  hydrogen.  Similarly, 
when  solutions  of  bases  are  electrolyzed  hydroxvl,  OH,  is  always  pro- 
duced as  a  primary  product  at  the  anode.  And,  here  again,  although 
hydroxyls  exist  in  many  compounds  other  than  those  having  basic 
properties,  it  is  only  from  solutions  of  these  that  hydroxyl  is  thus 
separated,  as  only  their  solutions  contain  the  ion,  hydroxidion.  And 
hydroxiodion  differs  further  from  hydroxyl  in  that  it  is  only  known 
in  solution,  that  it  blues  reddened  litmus,  and  that  it  is  replaceable 
by  acid  residues. 

In  the  electrolysis  of  an  oxyacid  (see  below)  that  group  which  is 
primarily  separated  at  the  positive  electrode  is  called  the  residue  of 
the  acid.  (See  p.  46.) 

Acids,  Bases  and  Salts. — All  ternary  and  quaternary  mineral 
substances  have  one  of  three  functions.  The  function  of  a  substance 
is  its  chemical  character  and  relationship,  and  indicates  certain  gen- 
eral properties,  reactions  and  decompositions  which  all  substances 
having  the  same  function  possess  and  undergo  alike.  Thus  in  mineral 
chemistry  we  have  acids,  bases  and  salts;  and  in  organic  chemistry, 
alcohols,  aldehydes,  acids,  ketones,  esters,  etc. 

An  acid  is  a  compound  of  an  electronegative  element  or  residue 
with  hydrogen,  which  hydrogen  it  can  part  with  in  exchange  for 
an  electropositive  element,  without  formation  of  a  base.  An  acid 
has  also  been  defined  as  a  compound  body  which  evolves  water  by 
its  action  upon  pure  caustic  soda  or  potash.  This  latter  definition 
is  undesirable  in  view  of  the  existence  of  certain  zinc  and  aluminium 
compounds  (pp.  175,  178).  No  substance  which  does  not  contain 
hydrogen  can,  therefore,  be  called  an  acid.  An  acid  has  also  boon 
defined  as  a  compound  yielding  hydrion  on  electrolysis. 

The  basicity  of  an  acid  is  the  number  of  replaceable  hydrogen 
atoms  in  its  molecule. 

A  monobasic  acid  is  one  containing  a  single  replaceable  atom  of 
hydrogen,  as  nitric  acid,  HN03 :  a  dibasic  acid  is  one  containing  two 
such  replaceable  atoms,  as  sulphuric  acid,  H2S04;  a  tribasic  acid  is 
one  containing  three  replaceable  hydrogen  atoms,  as  phosphoric  acid, 
H3P04.  Polybasic  acids  are  such  as  contain  more  than  one  atom  of 
replaceable  hydrogen. 

Hydracids  are  acids  containing  no  oxygen ;  oxyacids  contain  both 
hydrogen  and  oxygen. 

The  term  base  is  regarded  by  many  authors  as  applioablo  to  any 
compound  body  capable  of  neutralizing  an  acid.  It  is,  however,  moiv 
consistent  with  modern  views  to  limit  tho  application  of  the  name  to 
such  ternary  compound  substances  as  are  capable  of  entering  into 
double  decomposition  with  acids  to  form  salts  and  water.  They 
may  be  considered  as  one  or  more  molecules  of  water  in  which  one- 
half  of  the  hydrogen  has  been  replaced  by  an  electropositive  element 


ACIDS,  BASES  AND  SALTS  37 

or  radical ;  or  as  compounds  of  such  elements  or  radicals  with  one  or 
more  groups,  OH.  Being  thus  considered  as  derivable  from  water, 
they  are  also  known  as  hydroxides.  They  have  the  general  formula, 
M«(OH)n.  They  are  monatomic,  diatomic,  triatomic,  etc.,  accord- 
ing as  they  contain  one,  two,  three,  etc.,  groups  oxhydryl,  or  hy- 
droxyl  (OH).  As  acids  having  one,  two  or  three,  etc.,  atoms  of  re- 
placeable hydrogen  are  designated  as  monobasic,  dibasic,  or  tribasic 
acids,  etc.,  so  bases  having  one  replaceable  hydroxyl  are  spoken  of 
as  monacid  bases,  those  having  two  as  diacid  bases,  etc.  A  base 
has  also  been  defined  as  a  compound  yielding  hydroxidion  on 
electrolysis. 

The  atomicity  of  a  compound  is  the  number  of  hydroxyls  in  its 
molecule,  which  it  may  lose  by  their  combination  with  the  hydro- 
gen of  acids.  Bases  are  said  to  be  monatomic,  monohydric  or 
monacid ;  diatomic,  dihydric  or  diacid,  etc.,  according  as  the  number 
of  their  hydroxyls  is  one,  two,  etc. 

A  double  decomposition  is  a  reaction  in  which  both  of  the 
reacting  compounds  are  decomposed  to  form  two  new  compounds. 

Thiobases,  or  hydrosulphides,  are  compounds  in  all  respects 
resembling  the  bases,  except  that  in  them  the  oxygen  is  replaced  by 
sulphur. 

An  equivalent  of  an  acid  or  base  is  a  quantity  thereof  equal  to 
one  molecule,  divided  by  the  basicity  or  acidity;  or  that  propor- 
tionate quantity  of  its  molecular  weight  which  contains  only  one 
basic  hydrogen  atom  or  only  one  acid  displaceable  hydroxyl.  Thus,  a 
molecule  and  an  equivalent  of  potassium  hydroxide,  KOH,  both  weigh 
56.11 ;  a  molecule  of  sulphuric  acid,  H,S04,  weighs  98.08,  and  an 
equivalent  49.04. 

A  gram-equivalent  (gm  :eq.)  of  any  substance  is  a  quantity  thereof 
whose  weight  is  that  of  its  equivalent,  expressed  in  grams. 

Concentration. — By  the  "concentration"  or  "strength"  of  a  solu- 
tion is  understood  the  amount  of  the  solute  in  unit  volume  of  the 
solution  (not  of  the  solvent).  Various  units  are  used  for  the  ex- 
pression of  concentration: 

In  percentage  solutions,  strictly,  both  solvent  and  solute  are 
taken  in  parts  by  weight.  Thus,  a  4  per  cent,  solution  of  scdium 
chloride  is  made  with  4  gms.  NaCl  and  96  gms.  H20.  Volume:  per 
cent,  solutions  are  usually  more  convenient:  A  4- per  cent,  solution  of 
sodium  chloride  is  made  by  dissolving  4  gms.  NaCl  in  a  volume  of 
water  such  that  the  finished  solution  measures  100  cc.  The  difference 
between  per  cent,  and  v  per  cent,  solutions  is  more  marked  with 
solvents  other  than  water.  While  per  cert,  solutions  are  independent 
of  temperature,  v  per  cent,  solutions  have  the  concentration  indicated 
only  at  the  temperature  for  which  they  are  made,  which  is  usually 
18  °C. 

Normal   solutions  are  of  two  kinds:   Molecular-normal,   which 


38  TEXT-BOOK   OF   CHEMISTRY 

contain  one  gram-molecule  in  a  liter  of  solution,  and  Equivalent- 
normal,  which  contain  one  gram-equivalent  in  a  liter.  Thus,  one 
liter  of  M-N  solution  of  sulphuric  acid  contains  98  gms.  H2S04,  and 
one  liter  of  Eq-N  solution  49  gms.  Usually  "normal"  solutions 
are  molecular-normal,  except  solutions  used  in  volumetric  analysis, 
which  are  equivalent-normal,  whole  or  fractional.  Decinormal  solu- 
tions (—  j  contain  Mo  gm  :mol.  or  gm  :eq.  per  liter,  etc.  Standard 

solutions  are  solutions  of  some  fixed  volume-concentration,  which 
may  be  of  any  value  desired  for  the  use  intended. 

Salts  are  substances  formed  by  the  substitution  of  electro- 
positive, or  basylous,  elements  for  a  part  or  all  of  the  replaceable 
hydrogen  of  acids.  They  are  formed,  therefore,  when  bases  and  acids 
enter  into  double  decomposition. 

As  salts  are  produced  by  double  decomposition  between  acids  and 
bases,  the  latter  play  as  much  part  in  the  formation  of  salts  as  do  the 
former,  and  we  may  also  consider*the  salts  as  substances  formed  by 
the  substitution  of  acid  residues  (p.  46)  for  a  part  or  all  of  the 
hydroxyl  of  bases.  Salts  have  also  been  defined  as  compounds 
formed  by  the  union  of  the  anion  of  an  acid  and  the  cation  of 
a  base. 

It  will  be  seen  from  the  above  that  in  some  salts  the  hydrogen  of 

the  acid  is  only  partly  replaced,  as  in  baking  soda:  OC^Qjja.  Such 
salts  are  called  bi  salts  or  acid  salts.  There  exist,  also,  salts  in 
which  a  portion  of  the  hydroxyl  of  the  bases  is  retained.  Such  salts 
are  called  basic  salts,  e.  g.,  basic  lead  nitrate  N03PbOH.  (See  p.  45.) 

The  term  salt,  as  used  at  present,  applies  to  the  compounds  formed 
by  the  substitution  of  a  basylous  element  for  the  hydrogen  of  any 
acid;  and  indeed,  as  used  by  some  authors,  to  the  acids  themselves, 
which  are  considered  as  salts  of  hydrogen.  It  is  probable,  however, 
that  eventually  the  name  will  be  limited  to  such  compounds  as  cor- 
respond to  acids  whose  molecules  contain  more  than  two  elements. 
Indeed,  from  the  earliest  times  of  modern  chemistry  a  distinction  has 
been  observed  between  the  haloid  salts,  i.  e.,  those  the  molecules  of 
whose  corresponding  acids  consist  of  hydrogen,  united  with  one  other 
element,  on  the  one  hand ;  and  the  oxysalts,  the  salts  of  the  oxyacids, 
*.  e.,  those  into  whose  composition  oxygen  enters,  on  the  other  hand. 
This  distinction,  however,  has  gradually  fallen  into  the  background, 
for  the  reason  that  the  methods  and  conditions  of  formation  of  the 
two  kinds  of  salts  are  usually  the  same  ivhen  the  basylous  element  be- 
longs to  that  class  usually  designated  as  metallic. 

There  are,  however,  important  differences  between  the  two  classes 
of  compounds.  There  exist  compounds  of  all  of  the  elements  cor- 
responding to  the  hydracids,  binary  compounds  of  chlorine,  bromine, 
iodine  and  sulphur.  There  is,  on  the  other  hand,  a  large  class  of  ele- 
ments the  members  of  which  are  incapable  of  forming  salts  corre- 


ACIDS,  BASES  AND  SALTS  39 

spending  to  the  oxyacids.  No  salt  of  an  oxyacid  with  any  one  of  the 
elements  usually  classed  as  metalloids  (excepting  hydrogen)  has  been 
obtained. 

Haloid  salts  may  be  formed  by  direct  union  of  their  constituent 
elements;  oxysalts  are  never  so  produced. 

Action  of  Acids  and  Bases  on  Salts,  and  of  Salts  on  each 
other. —  (1)  If  an  acid  is  added  to  a  solution  of  a  salt  whose  acid 
it  nearly  equals  in  chemical  activity,  the  salts  of  both  acids  and  the 
acids  themselves  will  probably  exist  in  the  solution,  provided  both 
acids  and  salts  are  soluble.  Thus,  if  sulphuric  acid  is  added  to  a 
solution  of  potassium  nitrate,  the  solution  will  contain  potassium 
sulphate  and  nitrate,  and  sulphuric  and  nitric  acid : 

2H2S04+3KN03=K2S04+KN03+H2S04+2HN03 

(2)  If  an  acid  is  added  to  a  solution  of  a  salt  whose  acid  it 
greatly  exceeds  in  activity,  the  salt  is  decomposed,  with  formation 
of  the  salt  of  the  stronger  acid,  and  liberation  of  the  weaker  acid, 
both  salts  and  acids  being  soluble.    Thus,  if  sulphuric  acid  is  added 
to  a  solution  of  sodium  acetate,  the  solution  will  contain  sodium 
sulphate  and  acetic  acid: 

H2S04+2NaC2H302:=Na2S04+2HC2H302 

(3)  When  solutions  of  two  salts,  the  acids  of  both  of  which  form 
soluble  salts  with  both  bases,  are  mixed  the  resultant  liquid  contains 
the  four  salts.     Thus,  if  potassium  sulphate  and  sodium  nitrate  are 
dissolved  in  the  same  solution  it  will  contain  potassium  and  sodium 
sulphates  and  potassium  and  sodium  nitrates: 

3K2S04+3NaN03=r2K2S04+Na2S04+2KN03+NaN03, 

or  in  some  other  proportion. 

In  the  light  of  the  hypothesis  of  ionization,  the  statements  1,  2 
and  3,  while  applying  to  that  portion  of  the  compounds  which  remain 
un-ionized,  may  be  better  expressed  in  the  one:  Solutions  of  acids, 
bases  and  salts  contain  all  the  free  ions.  Thus,  in  the  example  given 
in  3,  the  solution  contains  K,  Na,  S04,  and  N03. 

(4)  If  to  a  solution  of  a  salt,  whose  acid  is  insoluble  in  the 
solvent  used,  an  acid  is  added,  capable  of  forming  a  soluble  salt 
with  the  basylous  element,  such  soluble  salt  is  formed  and  the  acid 
is  deposited.     Thus,  if  sulphuric  acid  is  added  to  an  aqueous  solu- 
tion of  sodium  stearate,  stearic  acid  will  be  deposited  and  sodium 
sulphate  formed: 

H2S04+2NaC18H8A=Na2S04+2HC18H8B02 

(5)  If  to  a  solution  of  a  salt  an  acid  is  added  which  is  capable 
of  forming  an  insoluble  salt  with  the  base,  such  insoluble  salt  is 
formed  and  precipitated.    Thus,  if  sulphuric  acid  is  added  to  a  solu- 


40  TEXT-BOOK   OF   CHEMISTRY 

tion  of  barium  nitrate,  barium  sulphate  is  precipitated  and  nitric 
acid  liberated: 

H2S04+Ba  (N03)  2=BaS04+2HN03 

(6)  If  to  a  solution  of  a  salt  whose  basylous  element  is  insoluble 
a  soluble  base  is  added,  capable  of  forming  a  soluble  salt  with  the 
acid,  such  soluble  salt  is  formed,  with  precipitation  of  the  insoluble 
base.    Thus,  if  potassium  hydroxide  is  added  to  a  solution  of  cupric 
sulphate,  cupric  hydroxide  is  precipitated  and  potassium  sulphate 
formed : 

2KOH+CuS04=Cu  ( OH)  2+K2S04 

(7)  If  a  base  is  added  to  a  solution  of  a  salt  with  whose  acid  it  is 
capable  of  forming  an  insoluble  salt,  such  insoluble  salt  is  formed 
and  precipitated,  and  the  base  of  the  original  salt,  if  insoluble,  is 
also  precipitated.     Thus  if  solutions  of  barium  hydroxide  and  of 
potassium  sulphate  are  mixed,  barium  sulphate  is  precipitated  and 
the  solution  contains  potassium  hydroxide : 

Ba(OH)2+K2S04=BaS04+2KOH; 

or  if  solutions  of  barium  hydroxide  and  silver  sulphate  are  mixed 
both  barium  sulphate  and  silver  hydroxide  will  be  precipitated: 

Ba(OH)2+Ag2S04=BaS04+2AgOH, 

and  if  the  substances   are   used   in  the   proportions   given   in   the 
equation  pure  water  will  remain. 

(8)  If  solutions  of  two  salts,  the  acid  of  one  of  which  is  capable  of 
uniting  with  the  base  of  the  other  to  form  an  insoluble  salt,  are 
mixed,   such  insoluble  salt   is   prec  'pitated.     Thus,    if   solutions   of 
barium  nitrate  and  of  sodium  sulphate  are  mixed,  barium  sulphate  is 
precipitated  and  sodium  nitrate  formed: 

Ba  (N03)  2+Na2S04=BaS04+2NaN03 

The  statements  4  to  8  may  ~be  summarized  in  tlie  statement: 
When  solutions  of  acids,  bases  or  salts  any  of  whose  ions  are  capable 
of  uniting  to  form  an  insoluble  compound  are  mixed,  such  insoluble 
compound  is  formed  and  precipitated. 

(9)  If  to  a  salt  whose  acid  is  volatile  at  the  existing  temperature 
an  acid  capable  of  forming  with  the  basylous  element  a  salt  fixed  at 
the  same  temperature  is  added,  the  fixed  salt  is  formed  and  the 
volatile  acid  expelled.     Thus,  with  the  application  of  heat,  sulphuric 
acid  expels  nitric  acid  from  sodium  nitrate  to  form  sodium  sulphate : 

H2S04+2NaN03=2HN03+Na2S04 

(10)  Similarly,  n  volatile  base  is  expelled  from  its  salts  by  a  fixed 
one.      Thus    potassium    hydroxide    and    ammonium    chloride    form 
ammonia,  water  and  potassium  chloride: 

KOH+NH4C1=KC1+NH3+H20 


STOICHICMETRY  41 

Stoidiiometry  in  its  strict  sense  refers  to  the  law  of  definite  pro- 
portions, and  to  its  applications.  In  a  wider  sense,  the  term  applies 
to  the  mathematics  of  chemistry,  i.  e.,  to  those  mathematical  calcu- 
lations by  which  the  quantitative  relations  of  substances  acting  upon 
each  other,  and  of  the  products  of  such  reactions  are  determined. 

A  chemical  reaction  can  -always  be  expressed  by  an  equation, 
which,  as  it  represents  not  only  the  nature  of  the  materials  involved, 
but  also  the  number  of  molecules  of  each,  is  a  quantitative  as  well  as 
a  qualitative  statement. 

Let  it  be  desired  to  determine  how  much  sulphuric  acid  will  be  re- 
quired to  completely  decompose  100  parts  of  sodium  nitrate,  and 
what  will  be  the  nature  and  quantities  of  the  products  of  the  decom- 
position. First  the  equation  representing  the  reaction  is  constructed  : 

H2S04  -f          2NaN03  Na2S04          -f          2HN03 

Sulphuric    acid.  Sodium   nitrate.  Disodic    sulphate.  Nitric    acid. 

which  shows  that  one  molecule  of  sulphuric  acid  decomposes  two 
molecules  of  sodium  nitrate,  with  the  formation  of  one  molecule  of 
sodium  sulphate  and  two  of  nitric  acid.  The  quantities  of  the  dif- 
ferent substances  are,  therefore,  represented  by  their  molecular 
weights,  or  some  multiple  thereof,  which  are  in  turn  obtained  by 
adding  together  the  atomic  weights  of  the  constituent  atoms: 

H2S04          -f          2NaN03  Na2SO4          -f          2HN03 


1X2=  2  23X1=23  23X2=46 

32X1=32  14X1  =  14  32X1=32  14x1  =  14 

16X4=64  16X3=48  16X4=64  16X3=48 

98  85X2=170  142  63x2=126 

Consequently,  98  parts  H2S04  decompose  170  parts  NaN03,  and 
produce  142  parts  Na2S04,  and  126  parts  HN03.  To  find  the  result 
as  referred  to  100  parts  NaN03,  we  apply  the  simple  proportion  : 

170:  100:  :    98:  57.64—57.64  =  parts  H2S04  required. 
170:  100:  :  142:  83.53—83.53  =     "       Na2S04  produced. 
170:  100::  126:  74.11—  74.11  =     "        HN03 

As  in  writing  equations,  the  work  should  always  be  proved  by 
adding  together  the  quantities  on  each  side  of  the  equality  sign, 
which  should  equal  each  other:  98+170=268=142+126=268,  or 
57.64+100=157.64=83.53+74.11=157.64. 

In  determining  quantities  as  above,  regard  must  be  had  to  the 
purity  of  the  reagents  used,  and,  if  they  be  crystallized,  to  the  amount 
of  water  of  crystallization  (see  p.  8)  they  contain. 

Let  it  be  desired  to  determine  how  much  crystallized  cupric  sul- 
phate can  be  obtained  from  100  parts  of  sulphuric  acid  of  92  per 


42  TEXT-BOOK   OF   CHEMISTRY 

cent,  strength.  As  cupric  sulphate  crystallizes  with  five  molecules  of 
water  of  crystallization  the  reaction  occurs  according  to  the  equation : 

H2S04  +  CuO  +  4H20  CuSO,5Aq. 

Sulphuric    acjd.  Cupric  oxide.  Water.  Cupric  sulphate. 

63  1X2=  2                              63x1=63 

1X2=    2                           16  16X1=16                               32X1=32 

32X1=32  16X4=64 

16X4=64  18X5=90 

98  79  18X4=72  249 

98+79+72=249 

98  parts  of  100  per  cent.  H2S04  will  produce,  therefore,  249  parts 
of  crystallized  cupric  sulphate.  But  as  the  acid  liquid  used  contains 
only  92  parts  of  true  H2S04,  in  100;  100  parts  of  such  acid  will 
yield  233.75  parts  of  crystallized  sulphate,  for  98 :  92 : :  249  :  233.75. 
Let  the  problem  be  to  determine  what  percentage  of  silver  is 
contained  in  a  silver  coin.  Advantage  is  taken  of  the  formation 
of  the  insoluble  silver  chloride,  A  piece  of  the  coin  is  chipped 
off  and  weighed:  weight  of  coin  used=2,5643  grams.  The  chip  is 
then  dissolved  in  nitric  acid,  forming  a  solution  of  silver  nitrate. 
From  this  solution  the  silver  is  precipitated  as  chloride,  by  the  addi- 
tion of  hydrochloric  acid,  according  to  the  equation: 

AgN03  +  HCl        =  AgCl          +  HN08 

Silver    nitrate.  Hydrochloric    acid.         Sliver   chloride.  Nitric   acid. 

108X1=108  1  108  1X1=  1 

14X1=  14  35.5  35.5  14x1  =  14 

16X3=  48  16X3=48 

170  36.5  143.5  63 

170+36.5=206.5=143.5+63. 

The  silver  chloride  is  collected,  dried  and  weighed : 

Weight  of  coin  used 2.5643  grams. 

Weight  of  AgCl  obtained 3.0665       " 

as  143.5  grams  AgCl  contain  108  grams  Ag— 143.5 : 108 ::  3.0665 : 
2.3078—2.5643  grams  of  the  coin  contain  2.3078  grams  of  silver  or 
90  per  cent.— 2.5643 : 100 : :  2.3078 :  90. 

Nomenclature. — The  names  of  the  elements  are  mostly  of  Greek 
derivation,  some  are  of  Latin  origin ;  some  of  Gothic  origin  and  others 
are  derived  from  modern  languages.  Very  little  system  has  been  fol- 
lowed in  naming  the  elements,  beyond  applying  the  termination  ium 
to  the  metals,  and  in  or  an  to  the  non-metals ;  and  even  to  this  rule 
there  are  exceptions,  such  as  a  metal  called  manganese  and  a  non- 
metal  called  sulphur. 


NOMENCLATURE  43 

The  names  of  compound  substances  were  formerly  chosen  upon  the 
same  system,  or  rather  lack  of  system,  as  those  of  the  elements.  So 
long  as  the  number  of  compounds  remained  small,  the  use  of  these 
fanciful  appellations  gave  rise  to  comparatively  little  inconvenience. 
In  these  later  days,  however,  when  the  number  of  compounds  known 
to  exist,  or  whose  existence  is  shown  by  approved  theory  to  be  pos- 
sible, is  practically  infinite,  some  systematic  method  of  nomenclature 
has  become  absolutely  necessary. 

The  principle  of  the  system  of  nomenclature  at  present  used 
is  that  the  name  shall  convey  the  composition  and  character  of 
the  substance. 

Compounds  consisting  of  two  elements,  or  of  an  element  and  a 
radical  only,  binary  compounds,  are  designated  by  compound  names 
made  up  of  the  name  of  the  more  electropositive,  followed  by  that 
of  the  more  electronegative,  in  which  the  termination  ide  has  been 
substituted  for  the  termination  in,  on,  ogen,  ygen,  orus,  ium,  and  ur. 
For  example :  the  compound  of  potassium  and  chlorine  is  called  potas- 
sium chloride,  that  of  potassium  and  oxygen  potassium  oxide,  that  of 
potassium  and  phosphorus  potassium  phosphide. 

In  a  few  instances  the  older  name  of  a  compound  is  used  in  prefer- 
ence to  the  one  which  it  should  have  under  the  above  rule;  such  are 
ammonia,  NH3 ;  water,  H20. 

When,  as  frequently  happens,  two  elements  unite  with  each  other 
to  form  more  than  one  compound,  these  are  usually  distinguished 
from  each  other  by  prefixing  to  the  name  of  the  element  varying  in 
amount  the  Greek  numeral  corresponding  to  the  number  of  atoms  of 
that  element,  as  compared  with  a  fixed  number  of  atoms  of  the  other 
element. 

Thus,  in  the  series  of  compounds  of  nitrogen  and  oxygen,  most  of 
which  contain  two  atoms  of  nitrogen,  N2  is  the  standard  of  com- 
parison, and  consequently  the  names  are  as  follows : 

N2O  =Nitrogen  monoxide. 

NO  (=NaO,)=Nitrogen  dioxide. 
N2O3  ^Nitrogen  frioxide. 

N02  ( =N2O4 )  =Nitrogen  tetroxide. 
N2O5  =Nitrogen  pentoxide. 

Another  method  of  distinguishing  two  compounds  of  the  same 
two  elements  consists  in  terminating  the  first  word  in  ous  in  that 
compound  which  contains  the  less  proportionate  quantity  of  the  more 
electronegative  element,  and  in  ic  in  that  containing  the  greater 
portion ;  thus : 

S02=Sulphurows  oxide. 

S03= Sulphuric  oxide. 

HgCl=Mercurows  chloride. 
HgCl2=Mercuric  chloride. 


44  TEXT-BOOK   OF   CHEMISTRY 

This  method,  although  used  to  a  certain  extent  in  speaking  of  com- 
pounds composed  of  two  elements  of  Class  III  (see  p.  52),  is  used 
chiefly  in  speaking  of  binary  compounds  of  elements  of  different 
classes. 

In  naming  the  oxyacids  the  word  acid  is  used,  preceded  by  the 
name  of  the  electronegative  clement  other  than  oxygen,  to  which  a 
prefix  or  suffix  is  added  to  indicate  the  degree  of  oxidation.  If  there 
are  only  two,  the  least  oxidized  is  designated  by  the  suffix  ous,  and 
the  more  oxidized  by  the  suffix  ic,  thus : 

HN02=NitroMs  acid. 
HNO3=Nitric  acid. 

If  there  are  more  than  two  acids,  formed  in  regular  series,  the  least 
oxidized  is  designated  by  the  prefix  liypo  and  the  suffix  ous;  the  next 
by  the  suffix  ous;  the  next  by  the  suffix  ic;  and  the  most  highly 
oxidized  by  the  prefix  per  and  the  suffix  ic;  thus : 

HC10=/f7ypochloroi<s  acid. 
HC102=Chloroi/s  acid. 
H01O3=Chlortc  acid. 
HClO4=Perchlonc  acid. 

Certain  elements,  such  as  sulphur  and  phosphorus,  exist  in  acids 
which  are  derived  from  those  formed  in  the  regular  way,  and  which 
are  specially  designated. 

The  names  of  the  oxysalts  are  derived  from  those  of  the  acids  by 
dropping  the  word  acid,  changing  the  termination  of  the  other  word 
from  ous  into  ite,  or  from  ic  and  ate,  and  prefixing  the  name  of  the 
electropositive  element  or  radical;  thus: 

HN02  KN02 

Nitrous  acid.  Potassium  nitrite. 

HN03  KN03 

Nitrfc  acid.  Potassium  nitrate. 

HC10  KC1O 

Hvpochlorous  acid.  Pota  slum  hypochlor/'fc. 

Acids  whose  molecules  contain  more  than  one  atom  of  replace- 
able hydrogen  are  capable  of  forming  more  than  one  salt  with  electro- 
positive elements,  or  radicals,  whose  valence  is  less  than  the  basicity 
of  the  acid.  Ordinary  phosphoric  acid,  for  instance,  contains  in  each 
molecule  three  atoms  of  basic  hydrogen,  and  consequently  is  capable 
of  for  ning  three  salts  by  the  replacement  of  one,  two,  or  three  of  its 
hydrogen  atoms,  by  one,  two,  or  three  atoms  of  a  univalent  metal. 
To  distinguish  these  the  Greek  prefixes  mono,  di,  and  tri  are  used,  the 
termination  inm  of  the  name  of  the  metal  being  changed  to  ic,  thus: 


RADICALS  45 

H2KP04=J/cwopotassic  phosphate. 
HK2P04:=Z)ipotasstc   phosphate. 
K3P04    :=7Vipotassic   phosphate. 

The  first  is  also  called  dihydropotassic  phosphate,  and  the  second, 
liydrodipotsissic  phosphate. 

In  the  older  works,  salts  in  which  the  hydrogen  has  not  been 
entirely  displaced  were  sometimes  called  bisalts  (e.g.,  bicarbonates), 
or  acid  salts ;  those  in  which  the  hydrogen  has  been  entirely  displaced 
being  designated  as  neutral  salts,  or  normal  salts. 

Some  elements,  such  as  mercury,  copper,  and  iron,  form  two  dis- 
tinct series  of  salts.  These  are  distinguished,  in  the  same  way  as  the 
acids,  by  the  use  of  the  suffix  ous  in  the  names  of  those  containing 
the  less  proportion  of  the  electronegative  group,  and  the  suffix  ic  in 
those  containing  the  greater  proportion,  e.  g.: 

Cu2SO4 (lS04:2Cu)  =Cuprows  sulphate. 

CuS04 (2S04:2Cu)  — Cupric  sulphate. 

FeS04 (2S04:2Fe)  =Ferrows  sulphate. 

Fe2(SO4)3    (3SO4:2Fe)=Fernc  sulphate. 

The  names,  basic  salts,  subsalts  and  oxysalts  have  been  applied 
indifferently  to  salts,  such  as  the  lead  subacetates,  which  are  com- 
pounds containing  the  normal  acetate  and  the  hydroxide  or  oxide  of 
lead;  and  to  salts  such  as  the  so-called  bismuth  subnitrate,  which  is 
a  nitrate,  not  of  bismuth,  but  of  the  univalent  radical,  bismuthyl 

(Bi'"0")'. 

By  double  salts  are  meant  such  as  are  formed  by  the  substitution 
of  different  elements  or  radicals  for  two  or  more  atoms  of  replace- 
able hydrogen  of  the  acid,  such  as  ammonium  magnesium  phosphate, 
P04Mg"(NH4)'. 

In  naming  the  cations,  the  termination  ion  is  added  to  the  stem 
of  the  name  of  the  metal,  the  Latin  name,  if  it  exists,  being  used ;  but 
sodion,  not  natrion,  and  potassion,  not  kalion.  Ionized  hydrogen  is 
called  liydrion.  The  names  of  the  anions  are  derived  from  those  of 
the  corresponding  salts  by  changing  the  terminations  from  ide  to 
idion,  e.  g.,  $"=sulphidion;  ite  to  osion,  e.  g.,  $03"=sulphosion;  and 
ate  to  anion,  e.  g.,  $0"4=sulp'hanion'  except  C03"  is  called  carbanion. 
The  anion  OH'  is  called  hydroxidion.  When  ions  of  different  valence 
are  derived  from  the  same  substance  they  are  distinguished  by  the 
corresponding  Greek  numerals.  Thus  the  electrolysis  of  H2S04  pro- 
ceeds in  two  stages,  first  H2S04=H'  |  HS04'=monosulphanion,  then 
HS04=IT  |  $04"=disulplianion. 

Radicals. — Many  compounds  contain  groups  of  atoms  which  pass 
from  one  compound  to  another,  and,  in  many  reactions,  behave  like 
elementary  atoms.  Such  groups  are  called  radicals,  or  compound 
radicals. 


46  TEXT-BOOK   OF   CHEMISTRY 

Marsh  gas  has  the  composition  CH4.  By  acting  upon  it  in  suitable 
ways  we  can  cause  the  atom  of  carbon,  accompanied  by  three  of  the 
hydrogen  atoms,  to  pass  into  a  variety  of  other  compounds,  such  as 
(CH3)C1,  (CH3)OH,  (CH3)20,  C2H302(CH3).  Marsh  gas,  therefore, 
consists  of  the  radical  (CH3)  combined  with  an  atom  of  hydrogen: 
(CH3)'H. 

It  is  especially  among  the  compounds  of  carbon  that  the  existence 
of  radicals  comes  into  prominent  notice.  They,  however,  occur  in 
inorganic  substances  also.  Thus  the  nitric  acid  molecule  consists  of 
the  radical  N02,  combined  with  the  group  OH. 

Like  the  elements,  the  radicals  possess  different  valences,  depend- 
ing upon  the  number  of  unsatisfied  valences  which  they  contain. 
Thus  the  radical  (CH3)  is  univalent,  because  three  of  the  four  val- 
ences of  the  carbon  atom  are  satisfied  by  atoms  of  hydrogen,  leaving 
one  free  valence.  The  radical  (PO)  of  phosphoric  acid  is  trivalent, 
because  two  of  the  five  valences  of  the  phosphorus  atom  are  satisfied 
by  the  two  valences  of  the  bivalent  oxygen  atom,  leaving  three  free 
valences. 

In  notation  the  radicals  are  usually  enclosed  in  brackets  as  above, 
to  indicate  their  nature.  The  names  of  univalent  radicals  terminate 
in  yl  or  in  gen;  thus:  (CH3)=methyl;  (CN)=cyanogen. 

The  terms  radical  and  residue  are  not  synonymous.  In  speaking 
of  acids  their  radicals  are  obtained  by  the  subtraction  of  a  number  of 
hydroxyls  equal  to  the  basicity  of  the  acid.  Thus  HN03 — H0= 
N02;  H2S04— 2HO=S02 ;  H3P04— 3HO=PO.  The  residue  is  that 
which  remains  after  removal  of  the  basic,  or  replaceable,  hydrogen. 
Thus:  HN03— H  =  N03;  H2S04  —  H2  =  S04;  H3P04  —  H3  =  P04 
(See  Electrolysis,  p.  33.)  The  anhydrides  (see  p.  61)  are  derived 
from  acids  by  removal  of  water.  Thus:  2HN03 — H20— N205; 
H2S04— H2p=S03;  2H3P04— 3H20=P205. 

Composition  and  Constitution. — The  characters  of  a  compound 
depend  not  only  upon  the  kind  and  number  of  its  atoms,  but  also 
upon  the  manner  in  which  they  are  attached  to  each  other.  There 
are,  for  instance,  two  substances,  each  having  the  empirical  formula 
C2H402,  one  of  which  is  a  strong  acid,  the  other  a  neutral  ester.  As 
the  molecule  of  each  contains  the  same  number  and  kind  of  atoms, 
the  differences  in  their  properties  must  be  due  to  differences  in  the 
manner  in  which  the  atoms  are  linked  together. 

The  composition  of  a  compound  is  the  number  and  kind  of 
atoms  contained  in  its  molecule ;  and  is  shown  by  its  empirical 
formula. 

The  constitution  of  a  compound  is  the  number  and  kind  of 
atoms  and  their  relations  to  each  other,  within  its  molecule ;  and  is 
shown  by  its  rational  formula. 

A  rational  formula  is  one  which  partly  or  completely  indicates  the 


COMPOSITION   AND   CONSTITUTION  47 

constitution  of  the  body.  Kational  formulae  are  either  typical  or 
graphic.  In  the  system  of  typical  formulae  all  substances  are  con- 
sidered as  being  so  constituted  that  their  rational  formulae  may  be 
referred  to  one  of  three  classes  or  types,  or  to  a  combination  of  two 
of  these  types.  These  three  classes,  being  named  after  the  most 
common  substance  occurring  in  each,  are  expressed  thus: 

The   hydrogen  The  water  The    ammonia 

type.  type.  type. 

H|  H  )  H 

H  f  H  fu  H  N 

H 

H2 )  Ha )  H2 

Ha  f  H2  f  °2  H2 

etc.,  etc.,  H2 

etc., 

it  being  considered  that  the  formula  of  any  substance  of  known  con- 
stitution can  be  indicated  by  substituting  the  proper  element,  or  radi- 
cal, for  one  or  more  of  the  atoms  of  the  type,  thus : 


)  (C2H5)O  cu     (S02)")_ 

f°  H  VN  Caf  H2  f°2 


cn     (C2H5)')  (C2H5)O  cu     (S02)" 

H  H 


Hydrochloric          Alcohol.  Ethylamine.  Calcium  Sulphuric 

acid.  chloride.  acid. 

Typical  formulae  are  of  great  service  in  the  classification  of  com- 
pound substances,  as  well  as  to  indicate,  to  a  certain  degree,  their 
nature  and  the  method  of  the  reactions  into  which  they  enter.  Thus 
in  the  case  of  the  two  substances  mentioned  above  (p.  46),  as  both 
having  the  composition  C2H402,  we  find  on  examination  that  one  con- 
tains the  group  (CH3)',  while  the  other  contains  the  group  (C2H30)'. 
The  difference  in  their  constitution  at  once  becomes  apparent  in  their 

typical  formulae,  ((CHJ''[0  and  *  jj^O,  indicating  differences  in 
their  properties,  which  we  find  upon  experiment  to  exist.  The  first 
substance  is  neutral  in  reaction  and  possesses  no  acid  properties;  it 

closely  resembles  a  salt  of  an  acid  having  the  formula  ((  E°H}O.  The 
second  substance,  on  the  other  hand,  has  a  strongly  acid  reaction, 
and  markedly  acid  properties,  as  indicated  by  the  oxidized  radical 
and  the  extra-radical  hydrogen.  It  is  capable  of  forming  salts  by 
the  substitution  of  an  atom  of  a  univalent,  basylous  element  for  its 

/  /"I    TT    S~\  \   f    \ 

single  replaceable  atom  of  hydrogen :          3N'a  j-  0. 

Although  typical  formulae  have  been  and  still  are  of  great  service, 
many  cases  arise,  especially  in  treating  of  the  more  complex  organic 
substances,  in  which  they  do  not  sufficiently  indicate  the  relations 
between  the  atoms  which  constitute  the  molecule,  and  thus  fail  to 
convey  a  proper  idea  of  the  nature  of  the  substance.  Considering, 


48  4  TEXT-BOOK   OF   CHEMISTRY 

for  example,  the  ordinary  lactic  acid,  we  find  its  composition  to  be 
C3H003,  which,  expressed  typically,  would  be  ^]£|O2I  a  constitu- 
tion supported  by  the  fact  that  the  radical  (C3H40)"  may  be  obtained 
in  other  compounds,  as  (  CaH4°ci"  |  •  This  constitution,  however,  can- 
not be  the  true  one,  because,  in  the  first  place  lactic  acid  is  not  di- 
basic, but  monobasic;  and  in  the  second  place,  there  is  another  acid, 
called  hydracrylic  acid,  having  an  identical  composition,  yet  differing 
in  its  products  of  decomposition.  These  differences  in  the  properties 
of  the  two  acids  must  be  due  to  a  different  arrangement  of  atoms 
in  their  molecules,  a  view  which  is  supported  by  the  sources  from 
which  they  are  obtained  and  the  nature  of  their  products  of  decom- 
position. 

To  express  the  constitution  of  such  bodies  graphic  formulae  are 
used,  in  which  the  position  of  each  atom  in  relation  to  the  others  is 
set  forth.  The  constitution  of  the  two  lactic  acids  would  be  expressed 
by  graphic  formulae  in  this  way: 

/H  /H 

C—  H  C—  H 

|\H  I  \0-H 

C/H  and  L/H 

|\0-H  |  \H 

J//o  Lr/d 

°\0-H  U 


or 

CH8  CH2OH 

CH.OH  and  CH2 

CH.OH  CH.OH 

Ordinary  Hydraerylic 

lactic   acid.  acid. 

Graphic  formulae  are  usually  still  further  abbreviated,  bonds  being 
indicated  by  dots;  thus:  CH3.  CHOH.  COOH,  and  CH2OH.  CH2. 
COOH. 

Chemical  Energy  —  Affinity  —  Displacement  —  Stability.  —  Chemi- 
cal energy,  frequently  spoken  of  as  chemical  affinity,  chemical  force, 
or  chemism,  is  that  form  of  energy  by  which  the  atoms  are  held 
together  in  the  molecule,  and  by  which,  under  suitable  physical  con- 
ditions, the  attachments  and  arrangement  of  atoms  are  changed. 

The  atoms  of  different  elements  do  not  exhibit  the  same  tendency 
to  enter  into  combination  with  the  atoms  of  a  given  element.  Thus 
chlorine  and  oxygen  readily  combine  with  hydrogen,  while  the  metals, 
except  the  alkaline  metals  and  palladium,  do  not  do  so  at  all.  Oxygen 
enters  into  the  combination  with  all  the  other  elements  except  fluorine 
and  the  elements  of  the  argon  group,  while  the  last-named  form  no 
compound  with  any  other  element.  Such  differences  in  tendency  to 


CHEMICAL   EQUILIBRIUM  49 

union  are  referred  to  by  saying  that  the  elements  have  strong  or 
weak  affinity. 

Frequently  when  an  element  is  brought  in  contact  with  a  com- 
pound the  free  element  displaces  one  of  those  contained  in  the  com- 
pound; as  when  chlorine  is  in  contact  with  sodium  iodide,  sodium 
chloride  is  formed  and  iodine  liberated:  2NaI+Cl2=2NaCl+I2. 
This  is  ascribed  to  the  greater  affinity  of  chlorine. 

There  are  also  differences  in  the  degree  of  permanence  of  com- 
pounds under  the  influence  of  slight  variations  in  physical  condi- 
tions. Thus,  of  the  two  compounds  of  hydrogen  and  oxygen,  one, 
water,  is  dissociated  only  at  very  high  temperatures,  while  the  other, 
hydrogen  dioxide,  is  decomposed  by  very  slight  heating.  These  varia- 
tions are  referred  to  by  saying  that  certain  compounds  are  stable, 
others  labile,  or  unstable.  The  stability  of  the  compound  depends 
upon  the  affinities,  the  proportions,  and  the  arrangement  of  the  atoms 
in  the  molecule. 

Chemical  Equilibrium. — When  two  or  more  substances  are 
brought  together,  their  association  constitutes  a  chemical  system. 
In  this  system  an  action  may  be  set  up,  which  will  proceed  to  a 
certain  point,  and  then  cease.  The  system  is  then  said  to  be  in 
chemical  equilibrium.  As  in  mechanical,  so  in  chemical  equilibrium 
the  condition  of  rest  does  not  imply  that  no  force  is  in  action,  but 
that  the  forces  acting  neutralize  each  other  in  such  manner  that 
their  algebraic  sum  is  zero;  the  condition  is  one  of  dynamic  equi- 
librium. 

As  the  "physical"  conditions  of  concentration,  pressure  and 
temperature  exert  great  influence  upon  the  occurrence  and  extent  of 
chemical  changes,  these  must  be  taken  into  account  along  with 
affinity;  and  the  "physical"  phenomena  of  solution,  and  changes  of 
state  of  aggregation  must  also  be  considered  along  with  changes  of 
composition  in  the  consideration  of  chemical  equilibrium. 

Equilibrium  in  a  system  all  parts  of  which  have  the  same  physical 
properties  and  the  same  chemical  composition,  as  in  a  solution  or 
in  a  mixture  of  liquids  or  of  gases,  is  distinguished  as  homogeneous 
equilibrium ;  while  heterogenous  equilibrium  occurs  in  a  system  the 
parts  of  which  are  separated  by  bounding  surfaces,  as  when  solids 
and  liquids,  or  immiscible  liquids  are  in  contact. 

Distinction  must  also  be  made  between  real  and  apparent  equilib- 
rium. In  a  state  of  real  equilibrium  there  is  no  change  of  relations, 
however  slight  or  however  slow,  so  long  as  the  conditions  of  con- 
centration, pressure  and  temperature  remain  constant,  and  changes 
which  are  caused  by  variations  in  these  conditions  take  place  regu- 
larly and  continuously.  Thus,  in  a  system  composed  of  a  solution  in 
contact  with  excess  of  the  solute,  variations  in  the  proportions  of  the 
solute  in  the  solution  take  place  regularly  with  variations  of  tempera- 
ture. Moreover,  in  this  case  the  same  condition  of  equilibrium  is 


50  TEXT-BOOK   OF   CHEMISTRY 

reached,  whether  it  is  approached  from  one  side  or  from  the  other. 
Thus,  a  solution  at  a  given  temperature  contains  the  same  proportion 
of  solute,  whether  it  is  obtained  by  addition  to  an  unsaturated  solu- 
tion, or  by  deposition  from  a  supersaturated  solution.  In  a  condition 
of  apparent  equilibrium  it  is  probable  that  change  is  continuously 
taking  place,  although  frequently  with  such  extreme  slowness  that  it 
escapes  observation,  even  at  constant  concentration,  temperature  and 
pressure.  Such  changes  as  are  caused  by  variations  in  these  condi- 
tions in  apparent  equilibrium  may,  within  certain  limits,  occur  with 
regularity,  but  beyond  these  limits  a  sudden  and  more  or  less  violent 
change  takes  place,  after  which  the  relations  which  existed  previously 
are  not  restored  by  a  return  to  the  original  conditions.  Thus,  in  a 
system  consisting  of  water  and  a  mixture  of  hydrogen  and  oxygen, 
with  moderate  variation  of  temperature  and  pressure  there  are  slight 
and  regular  variations  in  the  amount  of  oxygen  dissolved  in  the 
water,  but  at  a  certain  elevation  of  temperature  a  sudden  combination 
of  the  gases  to  form  water  takes  place  and,  on  cooling,  the  gases 
do  not  reappear. 

Reversible  Reactions. — Many  reactions  are  known  to  occur  in 
which  displacements  may  be  brought  about  in  opposite  directions. 
Clearly  in  these  some  influence  other  than  affinity  must  determine  in 
which  direction  the  reaction  will  occur.  Such  are  called  reversible 
reactions,  or  reversed  actions.  Thus,  if  iron  is  heated  in  an  atmos- 
phere of  vapor  of  water,  the  iron  displaces  the  hydrogen  of  the  water, 
which  is  liberated,  and  combines  with  the  oxygen  to  form  oxide  of 
iron.  If,  on  the  other  hand,  oxide  of  iron  is  heated  in  an  atmosphere 
of  hydrogen,  the  hydrogen  displaces  the  iron,  which  is  liberated,  and 
combines  with  the  oxygen  to  form  water.  The  reaction  may  take 
place,  therefore,  according  to  the  following  equation,  read  either 
from  left  to  right,  or  from  right  to  left: 

3Fe,          4.          8H20         <         >         2Fe304          -f          8H2 
Iron.  Water.  Trlferric    tetroxide.  Hydrogen. 

If  we  start  with  pure  iron  and  vapor  of  water  the  reaction  will 
proceed  according  to  the  equation  read  from  left  to  right  until  the 
proportion  of  hydrogen  and  water  vapor  present  has  reached  a  cer- 
tain ratio,  when  the  action  will  cease,  and  the  system  will  be  in 
equilibrium.  Starting  with  pure  oxide  of  iron  and  hydrogen,  on  the 
other  hand,  the  reaction  will  proceed  according  to  the  equation  read 
from  right  to  left,  and  will  cease  when  the  ratio  of  hydrogen  to  water 
vapor  will  have  acquired  the  same  value  as  that  reached  in  the  first 
instance.  As  the  condition  of  equilibrium  reached  in  the  two  cases  is 
the  same  when  produced  by  proceeding  in  either  direction,  it  is  one  of 
real  equilibrium,  and,  as  might  be  expected,  if  a  mixture  of  iron  and 
oxide  of  iron  be  heated  in  an  atmosphere  composed  of  hydrogen  and 


CLASSIFICATION   OF  ELEMENTS  51 

water  vapor  in  the  proportion  reached  in  either  of  the  two  former 
reactions,  no  change  whatever  will  occur. 

Mass  Action. — The  example  of  a  reversible  reaction  given  above 
was  one  in  a  heterogeneous  system,  composed  of  solids  and  gases. 
As  an  example  of  a  reaction  of  this  kind  occurring  in  a  homogeneous 
system,  a  solution,  we  may  consider  that  represented  by  the  following 
equation  : 

CH3.COOH      +      CH3.CH2OH     <        >     CH3.COO(C2H5)       -f      H2O. 

Acetic    acid.  Ethylic    alcohol.  Ethyl    acetate.  Water. 

If  we  start  with  ethyl  alcohol  and  acetic  acid,  the  reaction  will 
proceed  according  to  the  equation,  read  from  left  to  right ;  but  if  we 
start  with  ethyl  acetate  and  water  it  will  proceed  from  right  to  left. 
In  neither  case,  however,  will  it  be  complete.  If  one  mol  each  of  the 
reacting  substances  have  been  used,  real  equilibrium  will  have  been 
established  and  the  reaction  will  have  ceased  when  the  composition  of 
the  mixture  has  become:  %  mol  acetic  acid,  %  mol  alcohol,  %  mol 
ethyl  acetate  and  %  mol  water.  This  statement  is  not  to  be  taken  as 
meaning  that  when  this  relation  is  attained  no  further  action  occurs, 
but  that  the  changes  in  one  direction  have  become  equal  in  unit  time 
to  those  in  the  opposite  direction ;  the  equilibrium  being  dynamic,  not 
static. 

Chemical  effects  of  light. — Many  chemical  combinations  and  de- 
compositions are  much  modified  by  the  intensity,  and  the  kind  of 
light  to  which  the  reacting  substances  are  exposed.  Hydrogen  and 
chlorine  gases  do  not  combine,  at  the  ordinary  temperature,  in  the 
absence  of  light;  in  diffused  daylight  or  gaslight,  they  unite  slowly 
and  quietly;  in  direct  sunlight,  or  in  the  electric  light,  they  unite 
suddenly  and  explosively.  The  salts  of  silver,  used  in  photography, 
are  not  decomposed  in  the  dark,  but  are  rapidly  decomposed  in  the 
presence  of  organic  matter,  when  exposed  to  sunlight. 

Classification  of  the  Elements. — The  elements  were  formerly 
divided  into  two  great  classes,  metals  and  metalloids.  The  metals, 
being  such  substances  as  are  opaque,  possess  what  is  known  as 
metallic  luster,  are  good  conductors  of  heat  and  electricity,  and  are 
electropositive;  the  metalloids,  on  the  other  hand,  such  as  are 
gaseous,  or,  if  solid,  do  not  possess  metallic  luster,  have  a  compara- 
tively low  power  of  conducting  heat  and  electricity,  and  are  electro- 
negative. 

This  division,  based  upon  purely  physical  properties,  which,  in 
many  cases,  are  ill-defined,  has  become  insufficient.  Several  elements 
formerly  classed  under  the  above  rules  with  the  metals,  resemble  the 
metalloids  in  their  chemical  characters  much  more  closely  than  they 
do  any  of  the  metals.  Indeed,  by  the  characters  mentioned  above, 
it  is  impossible  to  draw  any  line  of  demarcation  which  shall  separate 
the  elements  distinctly  into  two  groups. 


52  TEXT-BOOK   OF   CHEMISTRY 

The  classification  of  the  elements  should  be  such  that  each  group 
shall  contain  elements  whose  chemical  properties  are  similar — the 
physical  properties  being  considered  only  in  so  far  as  they  are  inti- 
mately connected  with  the  chemical.  The  arrangement  of  elements 
into  groups  is  not  equally  easy  in  all  cases.  Some  groups,  as  the 
chlorine  group,  are  sharply  defined,  while  the  members  of  others 
differ  from  each  other  more  widely  in  their  properties.  The  position 
of  most  of  the  more  recently  discovered  elements  is  still  uncertain, 
owing  to  the  imperfect  state  of  our  knowledge  of  their  properties. 

In  this  book  the  elements  are  classified  according  to  resemblances 
in  their  chemical  properties,  based  upon  the  nature  of  the  oxides  and 
the  existence  or  non-existence  of  oxysalts: 


Class  I.     Typical  Elements. 
Hydrogen.     Oxygen. 

Although  these  two  elements  differ  notably  in  their  properties, 
they  are  here  classed  as  typical  elements,  because  together  they  form 
the  basis  of  our  classification ;  they  both  play  important  parts  in  the 
formation  of  acids;  neither  would  find  a  suitable  place  elsewhere  in 
the  classification ;  and  they  may  also  be  considered  as  typical  from 
the  point  of  view  of  ionization,  as  they  form  the  characterizing  ions 
of  acids  and  bases,  hydrion  and  hydroxidion. 


Class  II.     Elements  which  form  no  compounds. 
Helium,  neon,  argon,  krypton,  xenon,  niton. 

Class  III.     Acidulous  Elements. 

Elements  whose  oxides  unite  with  water  to  form  acids,  never  to 
form  bases.  Which  do  not  form  oxysalts. 

GROUP       I. — Fluorine,   chlorine,  bromine,   iodine. 

GROUP  II. — Sulphur,  selenium,  tellurium. 

GROUP  III. — Nitrogen,  phosphorus,  arsenic,  antimony. 

GROUP  IV. — Boron. 

GROUP  V. — Carbon,  silicon. 

GROUP  VI. — Vanadium,  columbium,  tantalum. 

GROUP  VII. — Molybdenum,  tungsten,  osmium. 

Elements  of  this  class  are  also  called  non-metah,  in  contradis- 
tinction to  those  of  classes  IV  and  V,  which  are  collectively  called 
metals.  They  are  also  referred  tn  as  electronegative  elements, 
because  they  are  electronegative  to  hydrogen,  although  they  are  all 


CLASSIFICATION   OF   ELEMENTS  53 

electropositive  to  oxygen,  and  individual  members  are  also  electro- 
positive to  others  of  the  class  (p.  34).  On  electrolysis  of  compounds 
containing  acidulous  elements  or  oxygen,  and  metals  or  hydrogen, 
the  former  are  usually  found  in  the  anion,  the  latter  in  the  cation,  as 
H  'K "  I  SO/'.  But  this  is  not  invariably  the  case. 


Class  IV.     Amphoteric  Elements. 

Elements  whose  oxides  unite  with  water,  some  to  form  bases,  others 
to  form  acids.  Which  form  oxysalts. 

GROUP  I.— Gold. 

GROUP  II. — Chromium,  manganese,  iron. 

GROUP  III. — Uranium,  radium,  thorium. 

GROUP  IV. — Lead. 

GROUP  V. — Bismuth. 

GROUP  VI. — Titanium,  germanium,  zirconium,  tin. 

GROUP  VII. — Palladium,  platinum. 

GROUP  VIII. — Rhodium,  ruthenium,  iridium. 

The  amphoteric  and  basylous  elements  are  the  metals  or  electro- 
positive elements,  and  have  these  properties  in  common:  they  form 
oxysalts,  and  are  separated  as  cations  on  electrolysis  of  such  salts. 


Class  V.     Basylous  Elements. 

Elements  whose  oxides  unite  with  water  to  form  bases,  never  to 
form  acids.  Which  form  oxysalts. 

GROUP         I. — Lithium,    sodium,    potassium,    rubidium,    caesium, 

silver. 

GROUP       II. — Thallium. 
GROUP     III. — Calcium,  strontium,  barium. 
GROUP      IV. — Magnesium,  zinc,  cadmium. 

GROUP        V. — Glucinum,  aluminium,  scandium,  gallium,  indium. 
GROUP      VI. — Nickel,  cobalt. 
GROUP    VII. — Copper,  mercury. 
GROUP  VIII. — Yttrium,  lanthanum,  cerium,  praseodymium,  neody- 

mium,  samarium,  gadolinium,  terbium,  thulium, 

ytterbium. 

This  class  includes  the  more  strongly  electropositive  metals. 

In  classes  III,  IV  and  V  the  elements  are  subdivided  into  groups, 
the  members  of  which  have  common  distinctive  characters,  and  are 
more  or  less  closely  allied  to  each  other.  In  classes  III  and  V  the 
resemblances  between  individuals  of  groups  occurring  first  in  the  list 


54 


TEXT-BOOK  OF   CHEMISTRY 


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PERIODIC   LAW  55 

are  the  most  marked,  and  are  more  close  than  those  between  members 
of  groups  placed  lower  down. 

Periodic  Law. — If  the  elements  are  arranged  in  a  continuous 
series  in  the  numerical  order  of  their  atomic  weights :  H,  He,  Li,  Gl, 
etc.,  it  will  be  found  that  elements  having  similar  properties,  in  them- 
selves and  in  their  compounds,  will  fall  in  the  same  (vertical)  line, 
or  group.  (See  table  on  p.  54.)  This  connection  between  the 
periodicity  of  the  atomic  weights  of  the  elements  and  their  chemical 
relationships  is  expressed  in  the  Periodic  law  of  Mendelejeff.  The 
properties  of  elements,  the  constitution  of  their  compounds,  and 
the  properties  of  the  latter  are  periodic  functions  of  the  atomic 
weights  of  the  elements.  But  the  law  is  not  absolute,  and,  apart 
from  the  necessity  of  a  few  transpositions,  the  separation  into  dif- 
ferent groups  of  such  closely  related  elements  as  Cu  and  Hg,  Cr  and 
Mn  and  Fe,  and  the  grouping  together  of  such  dissimilar  elements  as 
Cu,  Ag  and  Au  are  not  in  accordance  with  observed  fact. 

It  will  be  observed  that  the  series  is  complete,  with  but  a  single 
break,  between  H=l  and  Tb=159,  but  that  below  that  point  the 
breaks  are  numerous.  When  the  earlier  tables  were  constructed 
(about  1870)  the  breaks  were  more  numerous,  but  have  been  in  part 
filled  by  the  discovery  of  then  unknown  elements,  such  as  scandium, 
gallium,  germanium,  and  the  entire  argon  group.  It  may,  therefore, 
be  expected  that  other  breaks,  still  existing,  may  be  filled  by  the  dis- 
covery of  other  new  elements  of  very  high  or  very  low  atomic  weights. 


INORGANIC  CHEMISTRY 


CLASS  I.—  TYPICAL  ELEMENTS. 
HYDROGEN—  OXYGEN. 

ALTHOUGH,  in  a  strict  sense,  hydrogen  is  regarded  by  most 
chemists  as  the  one  and  only  type-element  —  that  whose  atom  is  the 
unit  of  atomic  and  molecular  weights  —  the  important  part  which 
oxygen  plays  in  the  formation  of  those  compounds  whose  nature 
forms  the  basis  of  our  classification,  its  acid-forming  power  in  organic 
compounds,  and  the  differences  existing  between  its  properties  and 
those  of  the  elements  of  the  sulphur  group,  with  which  it  is  usually 
classed,  warrant  us  in  separating  it  from  the  other  elements  and 
elevating  it  to  the  position  it  here  occupies. 

HYDROGEN. 

Symbol  =  H  —  Univalent  —  Atomic  weight  —  1  (International  = 
1.008)—  Molecular  weight—  2—  Sp.  gr.  =0.06926  A—  One  litre  weighs 
0.0899  gram  —  1  gram  measures  11.16  litres. 

Occurrence.  —  Occurs  free  in  volcanic  gases,  in  fire-damp,  occluded 
in  meteorites,  in  the  gases  exhaled  from  the  lungs,  and  in  those  of 
the  stomach  and  intestine.  In  combination  in  water,  acids,  hydrogen 
sulphide,  ammoniacal  compounds,  and  in  many  organic  substances. 

Preparation.  —  (1)  By  electrolysis  of  acidulated  water,  H  is  given 
off  at  the  negative  pole.  Utilized  .when  pure  H  is  required. 

(2)  By  the  dissociation  of  water  at  very  high  temperatures. 

(3)  By  the  decomposition  of  water  by  certain  metals.    The  alkali 
metals  decompose  water  at  the  ordinary  temperature: 

Na2  +  2H20  2NaOH          -f          H2 

Sodium.  Water.  Sodium  hydroxide.  Hydrogen. 

Some  other  metals,  such  as  iron  and  copper,  effect  the  decomposi- 
tion only  at  high  temperatures: 

3Fe2          -f          8H20  2Fe304          -f          8H2 

Iron.  Water.  Triferric  teroxide.  Hydrogen. 

(4)  By  decomposition  of  mineral  acids,  in  the  presence  of  water, 
by  zinc  and  certain  other  metals  : 


Zn       -f      H2S04      +      #H20     =     ZnS04       -f      H2      -f      #H2O 
Zinc.  Sulphuric    acid.          Water.       Zinc    sulphate.      Hydrogen.  Water. 

5? 


58  TEXT-BOOK   OF   CHEMISTRY 

Properties. — Physical. — Hydrogen  is  a  colorless,  odorless,  taste- 
less gas;  14.47  times  lighter  than  air,  being  the  lightest  substance 
known.  The  weight  of  a  litre,  0.0896  gram,  is  called  a  crith.  It  is 
almost  insoluble  in  water  and  alcohol.  It  conducts  heat  and  elec- 
tricity better  than  any  other  gas.  In  obedience  to  Graham's  law: 
The  diffusibility  of  two  gases  varies  inversely  as  the  square  roots 
of  their  densities,  it  is  the  most  rapidly  diffusible  of  gases.  The 
rapidity  with  which  this  diffusion  takes  place  renders  the  use  of 
hydrogen,  which  has  been^kept  for  even  a  short  time  in  gas  bags  or 
gasometers,  dangerous.  It  is  liquefied  at  — 240°  under  a  pressure  of 
13.3  atm.  The  liquid  is  clear  and  colorless,  boils  at  — 253°,  only  20° 
above  the  absolute  zero,  and  has  a  sp.  gr.  of  0.068. 

Certain  metals  have  the  power  of  absorbing  large  quantities  of 
hydrogen,  which  is  then  said  to  be  occluded,  and  this  action  of  the 
metal  is  called  occlusion.  Palladium  absorbs  980  volumes  of  the 
gas  when  used  as  the  negative  electrode  in  the  electrolysis  of  water. 
The  occluded  gas  is  driven  off  by  the  application  of  heat,  and 
possesses  great  chemical  activity,  similar  to  that  which  it  has  when 
in  the  nascent  state.  This  latter  quality,  and  the  fact  that  heat 
is  liberated  during  the  occlusion,  would  seem  to  indicate  that  the 
gas  is  contained  in  the  metal,  not  in  a  mere  physical  state  of  con- 
densation, but  in  chemical  combination. 

Chemical. — Hydrogen  exhibits  no  great  tendency  to  combine  with 
other  elements  at  ordinary  temperatures.  It  combines  explosively, 
however,  with  chlorine  under  the  influence  of  sunlight,  and  with 
fluorine  even  in  the  dark.  It  does  not  support  combustion,  but,  when 
ignited,  burns  with  a  pale  blue  and  very  hot  flame ;  the  result  of  the 
combination  being  water.  Mixtures  of  hydrogen  and  oxygen  ex- 
plode violently  on  the  approach  of  flame,  or  by  the  passage  of  the 
electric  spark,  the  explosion  being  caused  by  the  sudden  expansion 
of  the  vapor  of  water  formed,  under  the  influence  of  the  heat  of  the 
reaction.  In  a  mixture  of  hydrogen  and  oxygen  at  the  ordinary 
temperature  formation  of  water  takes  place  with  extreme  slowness. 
If  a  piece  of  platinum  foil  is  introduced  into  the  mixture  combina- 
tion occurs  with  sensible  rapidity,  and,  if  the  platinum  is  finely 
divided,  the  rapidity  of  the  combination  is  such  that  the  metal  be- 
comes incandescent,  and  explodes  the  mixture.  The  platinum  here  is 
said  to  be  a  catalyser,  i.e.,  a  substance  by  whose  presence  the  velocity 
of  a  reaction  is  accelerated.  Catalysers  are  also  called  contact 
agents.  Many  compounds  containing  oxygen  give  up  that  element 
when  heated  in  an  atmosphere  of  hydrogen: 

CuO          -f          Ha  Cu          -f       H20 

Cupric  oxide.  Hydrogen.  Copper.  Water. 

The  removal  of  oxygen  from  a  compound  is  called  a  reduction 
or  deoxidation.  In  a  broader  sense  the  term  reduction  is  applied  to 


OXYGEN  59 

any  diminution  in  the  relative  quantity  of  the  electronegative 
factor  in  a  compound.  Thus  mercuric  chloride,  HgCl2  (Hg  200:  Cl 
71)  Is  reduced  to  mercurous  chloride  HgCl  (Hg  200:  Cl  35.5). 

At  the  instant  that  H  is  liberated  from  its  compounds  it  has  a 
deoxidizing  power  similar  to  that  which  ordinary  H  possesses  only 
at  elevated  temperatures,  and  its  tendency  to  combine  with  other 
elements  is  greater  than  under  other  conditions.  The  greater 
energy  of  H,  and  of  other  elements  as  well,  in  this  nascent  state, 
may  be  thus  explained.  Free  H  exists  in  the  form  of  molecules, 
each  one  of  which  is  composed  of  two  atoms,  but  at  the  instant  of 
its  liberation  from  a  compound,  it  is  in  the  form  of  individual  atoms, 
and  that  portion  of  force  required  to  split  up  the  molecule  into 
atoms,  necessary  when  free  H  enters  into  reaction,  is  not  required 
when  the  gas  is  in  the  nascent  state. 

In  its  physical  and  chemical  properties,  hydrogen  more  closely 
resembles  those  usually  ranked  as  metals  than  it  does  those  forming 
the  class  of  non-metals,  among  which  it  is  usually  placed.  Its  con- 
ducting power,  as  well  as  its  relation  to  the  acids,  which  may  be 
considered  as  salts  of  H,  tend  to  separate  it  from  the  non-metals. 

Analytical  Characters. —  (1)  Burns  with  a  faintly  blue  flame, 
which  deposits  wrter  on  a  cold  surface  brought  over  it;  (2)  Mixed 
with  oxygen,  explodes  on  contact  with  flame,  producing  water. 

OXYGEN. 

Oxygenium  (U.  S.  P.)  Symbol=0 — Bivalent — Atomic  weight= 
16;  molecular  w eight =32.— Sp.  #r.=1.10563  A  (calculated=l.lOSS)  ; 
15.95  H. 

Occurrence. — Oxygen  is  the  most  abundant  of  the  elements.  It 
exists  free  in  atmospheric  air;  in  combination  in  a  great  number 
of  substances,  mineral,  vegetable,  and  animal ;  it  occurs  in  rocks  and 
minerals  (about  30  to  50  per  cent,  of  the  earth's  crust),  in  water  it 
is  eight-ninths  by  weight. 

Preparation. —  (1)  By  heating  certain  oxides: 

2HgO  =  2Hg  -f  02 

Mercuric    oxide.  Mercury.  Oxygen. 

3MnO2  Mn3O4  -f  O2 

Manganese  dioxide.         Trimanganic   tetroxide.  Oxygen. 

(2)  By  the  electrolysis  of  water,  acidulated  with  sulphuric  acid, 
0  is  given  off  at  the  positive  pole. 

(3)  By  the  action  of  sulphuric  acid  upon  certain  compounds  rich 
in    0 :    manganese    dioxide,    potassium    dichromate,    and    plumbic 
peroxide : 

2MnO2       -f         2H2SO4         =         2MnSO4         -f         2H2O         -f         O2 
Manganese    dioxide.     Sulphuric  acid.        Manganous  sulphate.  Water.  Oxygen. 


60  TEXT-BOOK   OF   CHEMISTRY 

(4)  The  best  method,  and  that  usually  adopted,  is  by  heating  a 
mixture  of  potassium  chlorate  and  manganese  dioxide  in  equal  parts. 
The  chlorate  gives  up  all  its  0,  according  to  the  equation : 

2KC103  =  2KC1  +  30, 

Potassium  chlorate.  Potassium  chloride.  Oxygen. 

A  small  quantity  of  free  chlorine  usually  exists  in  the  gas  pro- 
duced by  this  reaction.  If  the  oxygen  is  to  be  used  for  inhalation, 
the  chlorine  should  be  removed  by  allowing  the  gas  to  stand  over 
water  for  24  hours. 

(5)  By  the  decomposition  by  heat  of  certain  salts  rich  in  0: 
alkaline  permanganates,  nitrates  and  chlorates. 

(6)  By  the  action  of  water  upon  sodium  peroxide: 

2Na202  +  2H20    =  4NaOH     +    02 

Sodium  peroxide.  Water.          Sodium  hydroxide.       Oxygen 

Oxygen  is  official  in  the  U.  S.  P.  as  Oxygenium;  it  contains  not 
less  than  95  per  cent,  by  volume  of  0,  and  for  convenience  it  is 
usually  compressed  in  metal  cylinders. 

Properties. — Physical. — Oxygen  is  a  colorless,  odorless,  tasteless 
gas,  soluble  in  water  in  the  proportion  of  7.08  cc.  in  1  litre  of  water 
at  14.8°,  somewhat  more  soluble  in  absolute  alcohol.  It  liquefies  at 
—140°  under  a  pressure  of  300  atmospheres.  Liquid  oxygen  boils 
at  — 187.4°  at  the  ordinary  pressure. 

Chemical. — Oxygen  is  characterized,  chemically,  by  the  strong 
tendency  which  it  exhibits  to  enter  into  combination  with  other  ele- 
ments. It  forms  binary  compounds  with  all  elements  except  fluorine 
and  bromine.  With  most  elements  it  unites  directly,  especially  at 
elevated  temperatures.  In  many  instances  this  union  is  attended  by 
the  appearance  of  light,  and  always  by  the  extrication  of  heat.  The 
luminous  union  of  0  with  another  element  constitutes  the  familiar 
phenomenon  of  combustion,  and  is  the  principal  source  from  which 
we  obtain  so-called  artificial  heat  and  light.  A  body  is  said  to  be 
combustible  when  it  is  capable  of  so  energetically  combining  with 
the  oxygen  of  the  air  as  to  liberate  light  as  well  as  heat.  Gases  are 
said  to  be  supporters  of  combustion,  when  combustible  substances 
will  unite  with  them,  or  with  some  of  their  constituents,  the  union 
being  attended  with  the  appearance  of  heat  and  light.  The  distinc- 
tion between  combustible  substances  and  supporters  of  combustion 
is,  however,  one  of  mere  convenience.  The  action  taking  place  be- 
tween the  two  substances,  one  is  as  much  a  party  to  it  as  the  other. 
A  jet  of  air  burns  in  an  atmosphere  of  coal-gas  as  readily  as  a  jet  of 
coal-gas  burns  in  air. 

An  oxidation  is  a  chemical  action  in  which  oxygen  combines 
with  an  element  or  a  compound.  The  burning  of  coal:  C-|-0=CO 
or  C-}-02=:C02;  and  the  formation  of  acetic  acid  from  alcohol: 


OZONE  61 

C2H6+02=C2H402-f H20,  are  oxidations.  In  a  broader  sense  the 
word  " oxidation"  is  sometimes  used  as  the  opposite  to  "reduction" 
(p.  58)  to  apply  to  any  increase  in  the  relative  quantity  of  the  electro- 
negative element  in  a  compound.  Thus  the  conversion  of  FeCl2  (Fe 
56:C1  71)  into  FeCl3  (Fe  56:C1  106.5)  may  be  referred  to  as  an 
oxidation,  although  it  is,  more  properly,  a  chlorination. 

The  compounds  of  oxygen — the  oxides — are  divisible  into  three 
groups : 

1.  Anhydrides. — Oxides  capable  of  combining  with  water  to  form 
acids.     Thus  sulphuric  anhydride,  S03,  unites  with  water  to  form 
sulphuric  acid,  H2S04. 

The  term  anhydride  is  not  limited  in  application  to  binary  com- 
pounds, but  applies  to  any  substance  capable  of  combining  with  water 
to  form  an  acid.  Thus  the  compound  C4HG03  is  known  as  acetic 
anhydride,  because  it  combines  with  water  to  form  acetic  acid :  C4H603 
+H20=2C2H402.  (See  compounds  of  arsenic  and  sulphur.) 

2.  Basic  oxides  are  such  as  combine  with  water  to  form  bases. 
Thus  calcium  oxide,  CaO,  unites  with  water  to  form  calcium  hydrox- 
ide, CaH202. 

3.  Saline,  neutral  or  indifferent  oxides  are  such  as  are  neither 
acid  nor  basic  in  character.    In  some  instances  they  are  essentially 
neutral,  as  in  the  case  of  hydrogen  monoxide,  or  water.     In  other 
cases  they  are  formed  by  the  union  of  two  other  oxides,  one  basic, 
the  other  acid  in  quality,  such  as  the  red  oxide  of  lead,  Pb304,  formed 
by  the  union  of  a  molecule  of  the  acidulous  peroxide,  Pb02,  with 
two  of  the  basic  protoxide,  PbO.     It  is  to  oxides  of  this  character 
that  the  term  "saline"  properly  applies. 

The  process  of  respiration  is  very  similar  to  combustion,  and  as 
oxygen  gas  is  the  best  supporter  of  combustion,  so,  in  the  diluted 
form  in  which  it  exists  in  atmospheric  air,  it  is  not  only  the  best,  but 
the  only  supporter  of  animal  respiration.  (See  Carbon  dioxide.) 

Analytical  Characters. — 1.  A  glowing  match-stick  bursts  into 
flame  in  free  oxygen.  2.  Free  0,  when  mixed  with  nitrogen  dioxide, 
produces  a  brown  gas. 

OZONE. 

Allotropic  oxygen  (see  Allotropy,  p.  9). — Formula=Q3.  Mo- 
lecular weight— 48. — Air  through  which  discharges  of  static  electricity 
have  been  passed,  and  oxygen  obtained  by  the  decomposition  of 
water  (if  electrodes  of  gold  or  platinum  be  used),  have  a  peculiar 
odor,  somewhat  resembling  that  of  sulphur,  which  is  due  to  the 
conversion  of  a  part  of  the  oxygen  into  ozone. 

Preparation. —  (1)  By  the  decomposition  of  water  by  the  battery. 

(2)  By  the  slow  oxidation  of  phosphorus  in  damp  air. 

(3)  By  the  action  of  concentrated  sulphuric  acid  upon  barium 
dioxide : 


62  TEXT-BOOK    OF    CHEMISTRY 

3Ba02+3H2S04=3BaS04+3H20+03 

(4)  By  the  passage  of  silent  electric  discharges  through  air  or 
oxygen. 

Properties. — When  pure,  it  is  a  dark  liquid,  almost  opaque  in  lay- 
ers 2  mm.  thick,  which  is  not  decomposed  at  the  ordinary  temperature, 
but  converted  into  a  bluish  gas.  It'boils  at  — 119°. 

When  oxygen  is  ozonized  it  contracts  slightly  in  volume,  and 
when  the  ozone  is  removed  from  ozonized  oxygen  by  mercury  or 
potassium  iodide  the  volume  of  the  gas  is  not  diminished.  These 
facts,  and  the  great  chemical  activity  of  ozone,  haye  led  chemists 
to  regard  it  as  condensed  oxygen;  the  molecule  of  ozone  being 
represented  thus  (000),  while  that  of  ordinary  oxygen  is  (00): 
302=203. 

Ozone  is  very  sparingly  soluble  in  water,  more  soluble  in  the 
presence  of  hypophosphites,  insoluble  in  solutions  of  acids  and 
alkalies.  In  the  presence  of  moisture  it  is  slowly  converted  into 
oxygen  at  100°,  a  change  which  takes  place  rapidly  and  completely 
at  237  °.  It  is  a  powerful  oxidant ;  it  decomposes  solutions  of  potas- 
sium iodide  with  formation  of  potassium  hydroxide,  and  liberation 
of  iodine;  it  oxidizes  all  metals  except  gold  and  platinum,  in  the 
presence  of  moisture;  it  decolorizes  indigo  and  other  organic  pig- 
ments, and  acts  rapidly  upon  rubber,  cork,  and  other  organic 
substances. 

Analytical  Characters. — (1)  Neutral  litmus  paper,  impregnated 
with  solution  of  potassium  iodide,  is  turned  blue  when  exposed  to  air 
containing  ozone.  The  same  litmus  paper  without  iodide  is  not 
affected.  (2)  Manganous  sulphate  solution  is  turned  brown  by  ozone. 

(3)  Solutions  of  thallous  salts  are  colored  yellow  or  brown  by  ozone. 

(4)  Paper  impregnated  with  fresh  tincture  of  natural  (unpurified) 
guaiacum  is  colored  blue  by  ozone.     (5)  Metallic  silver  is  blackened 
by  ozone. 

When  inhaled,  air  containing  0.07  gram  of  ozone  per  litre  causes 
intense  coryza  and  hemoptysis.  It  is  probable  that  ozone  is  by  no 
means  as  constant  a  constituent  of  the  atmosphere  as  was  formerly 
supposed.  (See  Hydrogen  dioxide.) 

COMPOUNDS  OF  HYDROGEN  AND  OXYGEN. 

Two  are  known — hydrogen  monoxide  or  water,  H20;  hydrogen 
dioxide  or  oxygenated  water,  H202. 

WATER. 

H20 — Molecular  weight— IS — Sp.  gr.—\ — Vapor  density =0.6218 
A ;  calculated=Q.62M. 

Occurrence. — In  unorganized  nature  H20  exists  in  the  gaseous 


WATER  63 

form  in  atmospheric  air  and  in  volcanic  gases;  in  the  liquid  form 
very  abundantly ;  and  as  a  solid  in  snow,  ice,  and  hail. 

As  water  of  crystallization  it  exists  in  definite  proportions  in  cer- 
tain crystals,  to  the  maintenance  of  whose  shape  it  is  necessary. 

In  the  organized  world  H20  forms  a  constituent  part  of  every 
tissue  and  fluid. 

Formation. — Water  is  formed:  (1)  By  union,  brought  about  by 
elevation  of  temperature,  of  one  vol.  0  with  two  vols.  H. 

(2)  By  burning  H,  or  substances  containing  it,  in  air  or  in  0. 

(3)  By  heating  organic  substances  containing  H  to  redness  with 
cupric  oxide,  or  with  other  substances  capable  of  yielding  0.     This 
method  of  formation  is  utilized  to  determine  the  amount  of  H  con- 
tained in  organic  substances. 

(4)  When  an  acid  and  a  hydroxide  react  upon  each  other  to  form 
a  salt : 

H2S04        -f-         2KOH         =        K2S04        -f-        2H2O 

Sulphuric  acid.      Potassium  hydroxide.    Potassium  sulphate.          Water. 

(5)  When  a  metallic  oxide  is  reduced  by  hydrogen: 

CuO        +        H2        =        Cu        -f        H2O 

Cupric    oxide.  Hydrogen.  Copper.  Water. 

(6)  In  the  reduction  and  oxidation  of  many  organic  substances. 

Pure  H20  is  not  found  in  nature.  When  required  free  from  ordi- 
nary impurities  it  is  separated  from  suspended  matters  by  filtration, 
and  from  dissolved  substances  by  distillation. 

Properties. — Physical. — With  a  barometric  pressure  of  760  mm. 
H2O  is  solid  below  0°;  liquid  between  0°  and  100°;  and  gaseous 
above  100°. 

Water  is  the  best  solvent  we  have,  and  acts  in  some  instances  as 
a  simple  solvent,  in  others  as  a  chemical  solvent. 

Vapor  of  water  is  colorless,  transparent,  and  invisible.  The 
latent  heat  of  vaporization  of  water  is  536.5 ;  that  is,  as  much  heat  is 
required  to  vaporize  1  kilo,  of  water  at  100°  as  would  suffice  to  raise 
536.5  kilos,  of  water  1°  in  temperature.  In  passing  from  the  liquid 
to  the  gaseous  state,  water  expands  1,696  times  in  volume. 

Chemical. — Water  may  be  shown  to  consist  of  1  vol.  0  and  2  vols. 
H,  or  8  by  weight  of  0  and  1  by  weight  of  H,  either  by  analysis 
or  synthesis. 

Analysis  is  the  reducing  of  a  compound  to  its  constituent  parts 
or  elements. 

Synthesis  is  the  formation  of  a  compound  from  its  elements. 
A  partial  synthesis  is  one  in  which  a  complex  compound  is  produced 
from  a  simpler  one,  but  not  from  the  elements. 

Water  may  be  resolved  into  its  constituent  gases:   (1)   By  elec- 


64  TEXT-BOOK   OP   CHEMISTRY 

trolysis  of  acidulated  water;  H  being  given  off  at  the  negative  and 
0  at  the  positive  pole. 

(2)  By  passing  vapor  of  H20  through  a  platinum  tube  heated 
to  whiteness,  or  through  a  porcelain  tube  heated  to  about  1,100°. 
The  decomposition  of  a  compound  gas  or  vapor  by  elevation  of  tem- 
perature is  called  dissociation. 

(3)  By  the  action  of  the  alkali  metals.     Hydrogen  is  given  off, 
and  the  metallic  hydroxide  remains  in  solution  in  an  excess  of  H20. 

(4)  By  passing  vapor  of  H20  over  red-hot  iron.     Oxide  of  iron 
remains  and  H  is  given  off. 

Water  combines  with  oxides  to  form  new  compounds,  some  of 
which  are  acids  and  others  bases,  known  as  hydroxides. 

A  hydroxide  is  a  compound  formed  by  the  replacement  of  half 
of  the  hydrogen  of  water  by  another  element  or  by  a  radical. 

A  hydrate  is  a  compound  containing  chemically  combined 
water.  The  act  of  union  of  a  substance  with  water  is  referred  to  as 
hydration. 

The  hydroxides  of  the  electro-negative  elements  and  radicals  are 
acids;  most  of  those  of  the  electro-positive  elements  and  radicals 
are  basic  hydroxides. 

Certain  substances,  in  crystallizing,  combine  with  a  definite  pro- 
portion of  water,  which  is  known  as  water  of  crystallization,  and 
whose  presence,  although  necessary  to  the  maintenance  of  certain 
physical  characters,  such  as  color  and  crystalline  form,  does  not 
modify  their  chemical  reactions.  In  many  instances  a  portion  of  the 
water  of  crystallization  may  be  driven  off  at  a  comparatively  low 
temperature,  while  a  higher  temperature  is  required  to  expel  the 
remainder.  This  latter  is  known  as  water  of  constitution. 

The  symbol  Aq  (Latin,  aqua)  is  frequently  used  to  designate  the 
water  of  crystallization,  the  water  of  constitution  being  indicated  by 
H20.  Thus  MgS04,  H20+6Aq  represents  magnesium  sulphate  with 
one  molecule  of  water  of  constitution  and  six  molecules  of  water  of 
crystallization.  We  consider  it  preferable,  however,  as  the  distinc- 
tion between  water  of  crystallization  and  water  of  constitution  in 
many  salts  is  only  one  of  degree  and  not  of  kind,  to  use  the  symbol 
Aq  to  designate  the  sum  of  the  two ;  thus,  MgS04+7Aq. 

Water  decomposes  the  chlorides  of  the  third  class  (see  p.  52) 
of  elements  (those  of  carbon  only  at  high  temperatures  and  under 
pressure).  Thus  phosphorous  trichloride  forms  phosphorous  nnd 
hydrochloric  acids:  PC13+3H20:=H3PO.,+3HC1.  A  decomposition 
attended  with  absorption  of  water  is  called  hydrolysis. 

Natural  Waters. — Natural  waters  which  appear  to  the  senses  to  be  fit  for 
drinking  are  called  potable  waters,  in  contradistinction  to  such  as  are,  from 
their  taste  and  appearance,  obviously  unfit  for  that  use. 

Potable  waters  may  be  classified,  according  to  their  origin,  into  four  groups: 
(1)    Meteoric  waters:  rain  water  and  melted  snow.     These  are  the  purest 


WATER  65 

natural  wafers  if  uncontaminated ;  they  contain  very  small  quantities  of  solids, 
and  are^  highly  aerated.  Rain  water  falling  during  the  first  part  of  a  shower 
is  less  "pure  than  that  which  falls  subsequently.  In  districts  where  notable 
quantities  of  coal  which  contain  sulphur  are  burnt,  rain  water  contains  more 
sulphates,  ammoniacal  salts,  nitrates  and  nitrites  than  elsewhere. 

(2)  Surface  waters:  the  waters  of  rivers,  lakes  and  ponds.    These  are  mix- 
tures, in  varying  proportions,  of  rain  water,  spring  water  and  the  drainage  of 
the  surrounding  land.     They  vary  greatly  in  natural  purity,  and  are  frequently 
contaminated  by  sewage  and  other  refuse. 

(3)  Ground  waters:  water  which  permeates  the  superficial  stratum  above 
the  uppermost  impermeable  rock.     This  is  the  water  obtained  in  surface  wells 
and  in  driven  wells.     Its  quality  depends  upon  what  is  in  and  on  the  stratum 
in  which  the  well  is  dug;  a  driven  well  in  a  sandy  stratum  remote  from  habi- 
tations yields  an  excellent  water,  while  the  water  of  a  well  near  a  privy  vault 
or  a  defective   sewer   is  more  or   less  diluted   sewage.     In   limestone   districts 
ground  water  is  hard. 

(4)  Deep  waters:  spring  waters  and  those  of  artesian  wells. 

Spring  water  is  rain  water  which,  having  percolated  through  a  portion  of 
the  earth's  crust  (in  which  it  may  also  have  been  subjected  to  pressure),  has 
become  charged  with  solid  and  gaseous  matter,  varying  in  kind  and  quantity 
according  to  the  nature  of  the  strata  through  which  it  has  percolated,  the  dura- 
tion of  contact,  and  the  pressure  to  which  it  was  subject  during  such  contact. 

Spring  waters  from  igneous  rocks  and  from  the  older  sedimentary  forma- 
tions are  fresh  and  sweet,  and  any  spring  water  may  be  considered  such  whose 
temperature  is  less  than  20°,  and  which  does  not  contain  more  than  40  parts 
in  100,000  of  solid  matter;  provided  that  a  large  proportion  of  the  solid  matter 
does  not  consist  of  salts  having  a  medicinal  action,  and  that  sulphurous  gases 
and  sulphides  are  absent. 

Artesian  wells  are  artificial  springs,  produced  by  boring  in  a  low-lying  dis- 
trict, until  a  pervious  layer,  between  two  impervious  strata,  is  reached;  the 
outcrop  of  the  system  being  in  an  adjacent  elevated  regiom 

Properties  of  Potable  Waters. — A  water  to  be  fit  for  drinking  purposes 
should  be  cool,  limpid  and  odorless;  it  should  have  an  agreeable  taste,  neither 
flat,  salty,  nor  sweetish,  and  it  should  dissolve  soap  readily,  without  formation 
of  any  flocculent  precipitate.  But,  while  it  is  safe  to  condemn  a  water  which 
does  not  possess  the  above  characters,  it  is  by  no  means  safe  to  regard  all 
waters  which  do  possess  them  as  beyond  suspicion. 

Impurities. — The  most  dangerous  of  all  contaminations  of  drinking  waters 
is  by  admixture  of  sewage,  which  may  be  present  in  a  water  in  quantity 
sufficient  to  render  it  unfit  for  use  and  the  water  yet  retain  all  of  the  characters 
of  a  good  water  above  referred  to.  To  determine  whether  a  water  is  really  fit 
for  drinking  a  chemical  analysis  and  a  bacteriological  examination  are  necessary. 
For  both  of  these  methods  the  student  is  referred  to  treatises  on  that  subject. 
The  constituents  usually  determined,  and  the  interpretation  of  the  results,  are 
as  follows: 

Total  Solids. — The  amount  of  solid  material  dissolved  in  potable  waters 
varies  from  4.3  to  50  in  100,000  (2.5  to  29.2  grains  per  U.  S.  gal.);  and  a 
water  containing  more  than  the  latter  quantity  is  to  be  condemned  on  that 
account  alone. 

Chlorides. — The  presence  of  the  chlorides  of  the  alkaline  metals,  in  quan- 
tities not  sufficient  to  be  detectable  by  the  taste,  is  of  no  importance  per  se;  but 
in  connection  with  the  presence  of  organic  impurity,  a  determination  of  the 
amount  of  chlorine  affords  a  ready  method  of  indicating  the  probable  source  of 
the  organic  contamination.  As  vegetable  organic  matter  brings  with  it  but 
small  quantities  of  chlorides,  while  animal  contaminations  are  rich  in  those  com- 
pounds, the  presence  of  a  large  amount  of  chlorine  serves  to  indicate  that 


66  TEXTBOOK   OF   CHEMISTRY 

organic  impurity  is  of  animal  origin.  Indeed,  when  time  presses,  as  during  an 
epidemic,  it  is  best  to  rely  upon  determinations  of  chlorine,  and  condemn  all 
waters  containing  more  than  1.7  in  100,000  (1  grain  per  U.  S.  gal.)  of  that 
element. 

Hardness. — The  greater  part  of  the  solid  matter  dissolved  in  natural  fresh 
waters  consists  of  the  salts  of  calcium,  accompanied  by  less  quantities  of  the 
salts  of  magnesium.  The  calcium  salt  is  usually  the  bicarbonate  or  the  sulphate; 
sometimes  the  chloride,  phosphate,  or  nitrate. 

A  water  containing  an  excess  of  calcareous  salt  is  said  to  be  hard,  and  one 
not  so  charged  is  said  to  be  soft.  If  the  hardness  is  due  to  the  presence  of 
the  bicarbonate  it  is  temporary,  if  due  to  the  sulphate  it  is  permanent.  Cal- 
cium carbonate  is  almost  insoluble  in  pure  water,  but  in  the  presence  of  free 
carbonic  acid  the  more  soluble  bicarbonate  is  dissolved.  But,  on  the  water  being 
boiled,  it  is  decomposed,  with  precipitation  of  the  carbonate.  As  calcium  sul- 
phate is  held  in  solution  by  virtue  of  its  own,  albeit  sparing,  solubility,  it  is 
not  deposited  when  the  water  is  boiled;  the  addition  of  sodium  carbonate  per- 
manently softens  hard  water: 

CaS04-f-Na2C03=CaC03-}-Na2SO4. 

Rain  water  is  the  softest  water. 

The  hardness  is  now  usually  reported  in  terms  of  calcium  carbonate,  CaC03, 
either  in  grains  per  gallon  or  parts  in  100,000.  It  is  also  sometimes  reported 
in  "degrees,"  which  represent  grains  of  CaCO3  per  imperial  gallon.  Very  soft 
waters  contain  about  5CaCO3  in  100,000,  and  hard  waters  15  or  over.  Usually 
a  water  containing  more  than  20CaCO3  in  100,000  is  considered  too  hard  for 
domestic  use,  unless  softened  by  boiling.  But  a  water  is  not  to  be  condemned 
solely  because  its  hardness  exceeds  this  limit,  because  in  certain  limestone  dis- 
tricts all  waters  are  very  hard. 

Waters  which  owe  their  hardness  to  excess  of  magnesium  salts,  cause  in- 
testinal disturbances  in  those  not  habituated  to  them. 

Organic  Matter. — Technically,  organic  impurities  in  a  water  consist  of 
vegetable  or  animal  matters  containing  nitrogen.  We  have  seen  that  the  quan- 
tity of  chlorine  affords  an  indication  as  to  whether  the  organic  impurity  found 
to  be  present  is  of  vegetable  or  of  animal  origin.  Animal  organic  contamina- 
tion has  its  origin  in  sewage,  and  its  presence  consequently  indicates  that  the 
water  is,  or  may  at  any  moment  become,  the  means  of  transmitting  water- 
borne  diseases,  such  as  typhoid  and  cholera. 

The  nitrogenous  substances  in  feces  and  urine  consist  of  albuminous  bodies, 
crystalline  organic  compounds  (such  as  urea,  leucin,  etc.)  and  ammoniacal  salts. 
By  the  action  of  micro-organisms,  which  exist  in  the  soil  and  in  water,  the 
albuminous  and  crystalline  compounds  are  gradually  converted  into  ammonium 
compounds,  which  are  subsequently  oxidized  by  atmospheric  or  dissolved  oxygen, 
aided  by  bacterial  influence,  to  nitrites  and  later  to  nitrates.  Consequently  the 
amount  of  sewage  contamination,  and  the  degree  in  which  such  contamination 
has  been  subsequently  modified,  can  be  inferred  from  quantitative  determinations 
of  the  nitrogen  present  in  the  several  forms  referred  to. 

In  the  usual  process  of  water  analysis  the  following  factors  are  determined 
quantitatively : 

A.  Albuminoid  ammonia,  which  represents  the  nitrogen  present  in  albumi- 
nous and  crystalline  combination. 

B.  Free  ammonia,  which  represents  the  ammoniacal  compounds. 

C.  Nitrogen  in  nitrates  and  nitrites. 

D.  Nitrites. 

If  a  water  yields  no  albuminoid  ammonia  it  is  organically  pure,  even  if 
it  contains  much  free  ammonia  and  chlorides.  If  it  contains  from  .02  to  .05 
milligrams  per  litre  (.002  to  .005  in  100,000)  it  is  still  quite  pure.  When  the 


WATER  67 

albuminoid  ammonia  reaches  0.1  milligr.  per  litre  (.01  in  100,000)  the  water  is  to 
be  looked  upon  with  suspicion ;  and  it  is  to  be  condemned  when  the  proportion 
reaches  0.15  (.015  in  100,000). 

When  free  ammonia  is  also  present  in  considerable  quantity,  a  water 
yielding  0.05  (.005  in  100,000)  of  albuminoid  ammonia  is  to  be  looked  upon 
with  suspicion. 

Nitrates  and  nitrites  are  present  in  rain  water  in  quantities  less  than  0.5 
in  100,000,  calculated  as  nitrogen.  When  the  amount  exceeds  this,  these  salts 
are  considered  as  indicating  previous  contamination  by  organic  matter  which 
has  been  oxidized  and  whose  nitrogen  has  been  to  some  extent  converted  into 
nitrites  and  nitrates. 

The  quantity  of  nitrites  in  good  waters  does  not  exceed  .002  in  100,000 
when  they  are  present.  A  larger  quantity  is  considered  as  indicating  previous 
organic  contamination. 

Poisonous  Metals. — Natural  waters  containing  notable  quantities  of  iron 
compounds  belong  to  the  class  of  chalybeate  mineral  waters.  Contact  with 
metallic  iron  does  not  contaminate  water.  In  districts  where  copper  deposits 
exist  the  waters  sometimes  contain  copper,  and  the  waters  of  some  streams 
contain  arsenic. 

Lead  in  drinking  water  has  been  a  prolific  source  of  chronic  lead  poisoning. 
As  lead  is  only  dissolved  by  water  after  oxidation,  conditions  favoring  oxidation 
of  the  metal  favor  its  solution.  Such  conditions  are:  the  presence  of  nitrates, 
a  highly  aerated  condition  of  the  water,  alternate  wetting  and  drying  of  the 
surface  of  the  metal,  the  absence  of  sulphates  and  carbonates,  and  the  presence 
of  much  carbonic  acid  dissolved  under  pressure  (soda  water).  Sulphates  and 
carbonates  prevent  solution  by  the  formation  of  a  protecting  coating  of  an 
insoluble  salt.  As  a  rule,  the  purer  the  water  the  more  liable  it  is  to  dissolve 
lead  when  brought  in  contact  with  that  metal,  especially  if  the  contact  occurs 
when  the  water  is  at  a  high  temperature,  or  when  it  lasts  for  a  long  period. 

Purification  of  Water. — The  artificial  means  of  rendering  a  more  or  less 
contaminated  water  fit  for  use  are  of  five  kinds:  Distillation,  subsidence,  filtra- 
tion, precipitation,  and  boiling. 

Distillation  is  resorted  to  in  the  laboratory  to  obtain  very  pure  water, 
also,  on  a  larger  scale,  to  purify  drinking  water.  When  water  is  diitilled,  the 
first  portion  should  not  be  used,  because  it  contains  the  gaseous  impurities; 
and  the  last  part  should  not  be  used,  because  it  contains  the  solid  impurities. 
Distilled  water  is  official  in  the  U.  S.  P.  as  Aqua  destillata.  When  distilled 
water  is  to  be  used  for  drinking  it  should  be  aerated  and  charged  with  salts  to 
the  extent  of  about  0.03  gram  each  of  calcium  bicarbonate  and  sodium  chloride 
to  the  litre. 

In  filtration  suspended  impurities  are  removed  more  or  less  completely  by 
passing  the  water  through  a  porous  material.  In  filter  beds,  used  to  filter 
large  quantities  of  water,  sand  is  the  filtering  material  used,  either  alone  or 
combined  with  charcoal  or  spongy  iron.  In  domestic  filters,  treating  small 
quantities  of  water,  the  filtering  material  is  quartz  sand,  charcoal,  porous  stone, 
or  unglazed  earthenware  or  porcelain.  Whatever  may  be  the  size  or  construction 
of  the  filter,  it  must  be  cleaned  periodically.  If  this  is  neglected  the  filter 
ceases  to  purify  the  water,  and  becomes  itself  a  source  of  contamination.  Dis- 
solved organic  matter  is  in  part  removed  by  oxidation  in  filtration  through 
sand  filter  beds  several  feet  in  thickness,  or  through  much  thinner  layers  of 
charcoal  or  porous  iron.  Typhoid  and  cholera  germs  pass,  although  in  greatly 
diminished  numbers,  through  all  filters  except  those  made  of  unglazed  porcelain. 

Precipitation  methods  were  formerly  used  only  to  soften  temporarily  hard 
waters.  One  method  consists  in  the  addition  of  lime  water  in  quantity  just 
sufficient  to  convert  the  soluble  calcium  bicarbonate  present  into  the  insoluble 
carbonate.  At  present  precipitation  methods  are  also  used,  in  combination  with 


68  TEXT  BOOK   OF   CHEMISTRY 

subsidence  and  filtration,  to  remove  organic  impurities;  alum  or  a  ferric 
salt  is  added,  an  excess  being  avoided,  to  form  a  gelatinous  precipitate  which 
carries  the  impurities  down  with  it  mechanically  as  it  settles  when  the  water 
is  left  at  rest  in  the  subsidence  tanks;  the  water  in  drawn  oil  from  above  the 
deposit  to  the  filters,  after  a  proper  interval.  Precipitation  and  subsidence 
are  thus  used  to  diminish  the  work  required  of  the  filters. 

The  purification  of  water  by  boiling  can  only  be  carried  on  on  a  small 
scale.  It  is  very  useful,  however,  to  soften  temporarily  hard  waters  and,  par- 
ticularly, to  sterilize  infected  waters.  For  the  latter  purpose  the  boiling  must 
be  continued  actively  for  at  least  twenty  minutes  in  a  vessel  closed  except  for 
a  steam  outlet,  which  is  to  be  stopped  with  a  plug  of  cotton  when  the  vessel 
is  taken  off  to  cool. 

Natural  Purification  of  Water.— The  water  of  brooks,  rivers,  and*  lakes 
which  have  been  contaminated  by  sewage  and  other  organic  impurity  becomes 
gradually  purified  by  natural  processes.  Suspended  particles  are  deposited 
upon  the  bottom  and  sides  of  the  stream,  more  or  less  rapidly,  according  to 
their  gravity  and  the  rapidity  of  the  current.  The  bicarbonates  of  calcium, 
magnesium,  and  iron  gradually  lose  carbon  dioxide,  and  are  precipitated  as  car- 
bonates, which  mechanically  carry  down  dissolved  as  well  as  suspended  im- 
purities. The  decompositions,  oxidations,  and  reductions  to  whicli  organic  mat- 
ters are  subject  under  the  influence  of  atmospheric  and  dissolved  oxygen  and 
bacterial  action  bring  about  their  gradual  mineralization  by  conversion  into 
ammonia  and  then  into  nitrates.  The  processes  of  nutrition  of  aquatic  plant 
life  absorb  dissolved  organic  impurity,  as  well  as  the  products  of  decomposition 
of  nitrogenized  substances.  This  natural  purification  proceeds  the  more  rapidly 
the  more  contact  with  air  is  favored. 

Mineral  Waters. — Under  this  head  are  classed  all  waters  which  are  of 
therapeutic  or  industrial  value,  by  reason  of  the  quantity  or  nature  of  the 
dissolved  solids  which  they  contain;  or  which  have  a  temperature  greater 
than  20°. 

A  useful  classification  which  has  been  generally  adopted  includes  five 
classes : 

I.  Acidulous   icatcrs;   whose   value   depends   upon   dissolved    carbonic   acid. 
They   contain   but   small   quantities   of    solids,    principally   the   bicarbonates    of 
sodium  and  calcium  and  sodium  chloride. 

II.  Alkaline  waters;  which  contain  quantities  of  the  bicarbonates  of  sodium, 
potassium,  lithium,  and  calcium,  sufficient  to  communicate  to  them  an  alkaline 
reaction,  and  frequently  a  soapy  taste;  either  naturally,  or  after  expulsion  of 
carbon  dioxide  by  boiling. 

III.  Chalybeate  waters;  which  contain  salts  of  iron  in  greater  proportion 
than    4    parts    in    100,000.      They    contain    ferrous    bicarbonate    and    sulphate, 
calcium  carbonate,   sulphates   of   potassium,   sodium,   calcium,   magnesium,   and 
aluminium,  notable  quantities  of  sodium  chloride,  and  frequently  small  amounts 
of  arsenic.     They  have  the  taste  of  iron  and  are  usually  clear  as  they  emerge 
from  the  earth.     Those  containing  ferrous  bicarbonate   deposit   a   sediment  on 
standing,  by  loss  of  carbon  dioxide,  and  formation  of  ferrous  carbonate. 

IV.  Saline  icatcrs ;   which   contain  neutral   salts   in   considerable   quantity. 
The  nature  of  the  salts  which  they  contain  is  so  diverse  that  the  group  may 
well  be  subdivided: 

(a)  Chlorine  waters;  which  contain  large  quantities  of  sodium  chloride, 
accompanied  by  less  amounts  of  the  chlorides  of  potassium,  calcium,  and  mag- 
nesium. Some  are  so  rich  in  sodium  chloride  that  they  are  not  of  service  as 
therapeutic  agents,  but  are  evaporated  to  yield  a  more  or  less  pure  salt.  Any 
natural  water  containing  more  than  300  parts  in  100,000  of  sodium  chloride 
belongs  to  this  class,  provided  it  does  not  contain  substances  more  active  in  their 
medicinal  action  in  such  proportion  as  to  warrant  its  classification  elsewhere. 


HYDROGEN  DIOXIDE  69 

Waters  containing  more  than  1,500  parts  in  100,000  are  too  concentrated  for 
internal  administration. 

(•&)  ~  Sulphate  ivaters  are  actively  purgative  from  the  presence  of  consider- 
able proportions  of  the  sulphates  of  sodium,  calcium,  and  magnesium.  Some 
contain  large  quantities  of  sodium  sulphate,  with  mere  traces  of  the  calcium  and 
magnesium  salts,  while  in  others  the  proportion  of  the  sulphates  of  magnesium 
and  calcium  is  as  high  as  3,000  parts  in  100,000  to  2,000  parts  in  100,000  of 
sodium  sulphate.  They  vary  much  in  concentration;  from  500  to  nearly  6,000 
parts  of  total  solids  in  100,000.  They  have  a  salty,  bitter  taste,  and  vary  much 
in  temperature. 

(c)  Bromine  and  Iodine  waters  are  such  as  contain  the  bromides  or  iodides 
of  potassium,  sodium,  or  magnesium  in  sufficient  quantity  to  communicate  to 
them  the  medicinal  properties  of  those  salts. 

V.  Sulphurous  waters;  which  hold  hydrogen  sulphide  or  metallic  sulphides 
in  solution.  They  have  a  disagreeable  odor  and  are  usually  warm.  They  contain 
20  to  400  parts  in  100,000  of  total  solids. 

Physiological. — Water  is  taken  into  the  body  both  as  a  liquid 
and  as  a  constituent  of  every  article  of  food;  the  amount  ingested 
by  a  healthy  adult  being  2.25  to  2.75  litres  (2Vs  to  3  quarts)  a  day. 
The  greater  the  elimination  and  the  drier  the  nature  of  the  food  the 
greater  is  the  amount  of  H20  taken  in  the  liquid  form. 

Water  is  a  constituent  of  every  tissue  and  fluid  of  the  body,  vary- 
ing from  0.2  per  cent,  in  the  enamel  of  the  teeth  to  99.5  per  cent,  in 
the  perspiration  and  saliva.  It  constitutes  about  60  per  cent,  of  the 
weight  of  the  body. 

The  consistency  of  the  various  parts  does  not  depend  entirely  upon 
the  relative  proportion  of  solids  and  HL,0,  but  is  influenced  by  the 
nature  of  the  solids.  The  blood,  although  liquid  in  the  ordinary  sense 
of  the  term,  contains  a  less  proportional  amount  of  H20  than  does  the 
tissue  of  the  kidneys,  and  about  the  same  proportion  as  the  tissue  of 
the  heart.  Although  the  bile  and  mucus  are  not  as  fluid  as  the  blood, 
they  contain  a  larger  proportion  of  H20  to  solids  than  does  that 
liquid. 

Water  is  discharged  by  the  kidneys,  intestines,  skin,  and  pulmo- 
nary surfaces.  The  quantity  discharged  is  greater  than  that  ingested ; 
the  excess  being  formed  in  the  body  by  the  oxidation  of  the  H  of  its 
organic  constituents. 

HYDROGEN  DIOXIDE. 

HYDROGEN  PEROXIDE— OXYGENATED  WATER. 
H202— Molecular  weight=34—Sp.  #r.=1.455. 

Occurence. — Exists  naturally  in  very  minute  quantity  in  rain- 
water, in  air,  and  in  the  saliva. 

Preparation. — (1)  It  may  be  obtained,  mixed  with  a  large  quan- 
tity of  H20,  by  the  action  of  dilute  mineral  acids  on  barium  dioxide : 
Ba02+H2S04=:BaS04+H202 


70  TEXT-BOOK   OF   CHEMISTRY 

(2)  It  is  also  formed  in  small  quantity  during  the  slow  oxidation 
of  many  elements  and  compounds,  such  as  P,  Pb,  Zn,  Cd,  Al,  alcohol, 
ether  and  the  essences. 

(3)  It   is   prepared   industrially   of    10-12   volume   strength    by 
gradually  adding  barium  dioxide  to  dilute  hydrofluoric  acid  solution, 
the  mixture  being  maintained  at  a  low  temperature  and  constantly 
agitated. 

(4)  In  still  greater  concentration  by  the  action  of  dilute  acids  on 
sodium  dioxide,  care  being  had  to  prevent  heating  of  the  mixture : 

Na2O2+2HCl=2NaCl+H202 

(5)  Hydrogen  dioxide  is  also  formed  when  sodium  dioxide  is  dis- 
solved in  water : 

Na202+2H20=2NaOH+H202 

Properties. — The  pure  substance  is  a  colorless,  syrupy  liquid, 
which,  when  poured  into  H20,  sinks  under  it  before  mixing.  It  has 
a  disagreeable  metallic  taste,  somewhat  resembling  that  of  tartar 
emetic.  When  taken  into  the  mouth  it  produces  a  tingling  sensation, 
increases  the  flow  of  saliva,  and  bleaches  the  tissues  with  which  it 
comes  in  contact.  It  is  still  liquid  at  — 30°.  It  is  very  unstable, 
and,  even  in  darkness  and  at  ordinary  temperature,  is  gradually  de- 
composed. At  20°  the  decomposition  takes  place  more  quickly  and 
at  100°  rapidly  and  with  effervescence.  The  dilute  substance,  how- 
ever, is  comparatively  stable,  and  may  be  boiled  and  even  distilled 
without  suffering  decomposition.  Yet  it  is  liable  to  explosive  de- 
composition when  exposed  to  summer  temperature  in  closed  vessels. 

Hydrogen  dioxide  acts  both  as  a  reducing  and  an  oxidizing  agent. 
Arsenic,  sulphides,  and  sulphur  dioxide  are  oxidized  by  it  at  the 
expense  of  half  its  oxygen.  When  it  is  brought  in  contact  with  silver 
oxide  both  substances  are  violently  decomposed,  water  and  ele- 
mentary silver  remaining.  By  certain  substances,  such  as  gold, 
platinum,  and  charcoal  in  a  state  o-  fine  division,  fibrin,  or  manga- 
nese dioxide,  it  is  decomposed  with  evolution  of  oxygen;  the  decom- 
posing agent  remaining  unchanged. 

The  pure  substance,  when  decomposed,  yields  475  times  its  volume 
of  oxygen ;  the  dilute  15  to  20  volumes. 

In  dilute  solution  it  is  used  as  a  bleaching  agent  and  in  the  reno- 
vation of  old  oil-paintings.  It  is  an  energetic  disinfectant  and  anti- 
septic, and  is  used  in  surgery.  "Ozonic  ether"  is  a  mixture  of 
ethylic  ether  and  dilute  hydrogen  dioxide. 

Solution  of  Hydrogen  Dioxide — Liquor  Hydrogenii  Dioxidi 
(U.  S.  P.) — is  an  aqueous  solution  containing  not  less  than  3  per 
cent,  by  weight  of  H,02,  and  corresponding  to  not  less  than  10  vol- 
umes of  available  oxygen. 

Analytical  Characters. —  (1)  To  a  solution  of  starch  a  few  drops 
of  cadmium  iodide  solution  are  added,  then  a  small  quantity  of  Ili<> 


HYDROGEN   DIOXIDE  71 

fluid  to  be  tested,  and,  finally,  a  drop  of  a  solution  of  ferrous  sul- 
phate. A  blue  color  is  produced  in  the  presence  of  hydrogen  dioxide 
even  if  the  solution  contain  only  0.05  milligram  per  litre. 

(2)  Add  freshly-prepared  tincture  of  guaiacum  and  a  few  drops 
of  a  cold  infusion  of  malt.    A  blue  color — 1  in  2,000,000. 

(3)  Add  to  the  liquid  a  few  drops  of  potassium  dichromate  and 
a  little  dilute  sulphuric  acid,  and  agitate  with  ether.     The  ether 
assumes  a  brilliant  blue-violet  color. 


CLASS  II.— ELEMENTS  WHICH  FORM  NO  COMPOUNDS. 
HELIUM.     NEON.     ARGON.     KRYPTON.     XENON.     NITON. 

The  elements  of  this  group  have  been  recently  discovered,  and 
exist  in  air  and  in  certain  minerals.  As  they  form  no  compounds, 
their  atomic  weights  are  not  known,  although,  from  their  molecular 
heats,  there  is  reason  to  believe  that  their  molecular  symbols  are  He, 
etc.,  not  He2,  etc. 

Argon,  the  most  abundant  of  the  class,  was  discovered  by  Ray- 
leigh  and  Ramsay  in  1894  in  air,  in  which  it  exists  in  the  propor- 
tion of  0.9  in  100  by  volume,  and  1.2  per  cent,  by  weight.  It  is  a 
transparent,  colorless,  odorless,  tasteless  gas;  sp.  gr.=19.941;  Mw.= 
40  (International=39.88).  At  the  normal  pressure  it  liquefies  at 
—186.9°,  forming  a  colorless  liquid  of  sp.  gr.  1.5.  It  solidifies  at 
—190°.  It  is  sparingly  soluble  in  water:  4.05  in  100.  It  is  obtained 
from  atmospheric  air  as  a  residue  by  causing  the  other  constituents 
to  enter  into  combination.  When  rarefied  it  gives  a  characteristic 
spectrum  of  many  lines  with  the  induction  spark. 

Helium  owes  its  name  to  the  fact  that  its  existence  in  the  sun's 
atmosphere  was  recognized  by  the  characteristic  line  D3  of  the  solar 
spectrum  before  it  was  discovered  as  a  terrestrial  element.  It  exists 
in  certain  rare  uranium  minerals,  and  in  some  spring  waters.  It  is  a 
very  light  gas:  Mw.=4. 

The  other  members  of  the  class:  Neon:  Mw.=20  ( International = 
20.2)  ;  Krypton:  Mw.=83  (International=82.92)  ;  and  Xenon:  Mw. 
=130  (International=130.2),  have  been  found  in  small  amount  in 
the  residue  of  evaporation  of  liquefied  air. 

Niton:  Mw.=222  (International=222.4),  radium  emanation,  also 
belongs  to  this  group. 

It  has  been  estimated  that  these  gases  are  present  in  air,  in  about 
the  following  proportions : 

Argon            0.9  part    in  100  of  air. 

Neon        1  to  2  parts  in  100,000  of  air. 

Krypton           1  part    in  1,000,000  of  air. 

Helium     1  to  2  parts  in  1,000,000  of  air. 

Xenon              1  part    in  20,000,000  of  air. 


72 


CLASS  III.— ACIDULOUS  ELEMENTS. 

Elements  all  of  whose  Hydrates  are  Acids  and  which  do  not  form  Salts  with 

the  Oxyacids. 

I.     CHLORINE  GROUP. 
FLUORINE.     CHLORINE.     BROMINE.     IODINE. 

The  elements  of  this  group,  known  as  the  halogens,  closely 
resemble  each  other  in  their  chemical  properties  and  in  the  structure 
and  properties  of  their  compounds,  fluorine  differing  more  from  the 
other  three  than  these  do  from  each  other.  They  are  univalent  in 
the  great  majority  of  the  compounds  into  whose  formation  they  enter, 
although  they  are  sometimes  trivalent,  as  in  IC13.  With  hydrogen 
each  forms  an  acid  compound,  composed  of  one  volume  of  the  halogen 
in  the  gaseous  state  with  one  volume  of  hydrogen.  All  mineral 
acids  into  whose  composition  they  enter  are  monobasic.  Fluorine  is  a 
gas,  liquefiable.  with  difficulty,  chlorine  an  easily  liquefiable  gas, 
bromine  a  liquid,  and  iodine  a  solid  at  the  ordinary  temperature  and 
pressure.  The  relations  of  their  compounds  to  each  other  are  shown 
in  the  following  table : 


J1X1 

HC1 
HBr 
HI 

Hydro-ic 

C12O 

CIA 

HC1O 
HBrO 
HIO 

Hypo- 

HC102 

HC103 
HBr08 
HI03 

-ic  acid. 

HC104 
HBr04 
HIO4 

Per-ic 

I204 

Tetroxide. 

HI02 
-ous  acid. 

Monoxide. 

acid.  ous  acid.  acid. 

FLUORINE. 


=F  —  Atomic  weight—  19   (International=19.Q).  —  Molecu- 
lar weigJit—3S.—Sp.  gr.  1.265  A  (calculated—  1.316)  . 

Fluorine  has  been  isolated  by  the  electrolysis  of  pure,  dry  HF  at 
—  23  °.  It  exists  in  nature  chiefly  in  Fluor-Spar,  CaF2,  and  in  cryolite, 
A12F6  (NaF)G. 

It  is  a  gas,  colorless  in  thin  layers,  greenish  yellow  in  thick  layers. 
It  decomposes  H20,  with  formation  of  HF  and  ozone.  In  it  Si,  B, 
As,  Sb,  S,  and  I  fire  spontaneously.  With  H  it  detonates,  even  in  the 
dark.  It  attacks  organic  substances  violently.  The  apparatus  in 
which  it  is  liberated  must  be  made  of  platinum  or  fluor-spar.  It 
forms  compounds  with  all  other  elements  except  oxygen. 

Hydrogen  Fluoride.  —  Hydrofluoric  acid=H~F  —  Molecular  weight 
=20.  Hydrofluoric  acid  is  obtained  by  the  action  of  an  excess  of 

73 


74  TEXT-BOOK   OF   CHEMISTRY 

sulphuric  acid  upon  fluor-spar  or  upon  barium  fluoride,  with  the  aid 
of  gentle  heat: 

CaF2+H2S04=CaS04+2HF. 

If  a  solution  is  desired,  the  operation  is  conducted  in  a  platinum 
or  lead  retort,  whose  beak  is  connected  with  a  U-shaped  receiver  of 
the  same  metal,  which  is  cooled  and  contains  a  small  quantity  of 
water. 

The  pure  acid  is  a  colorless  liquid,  which  boils  at  19  °  and  solidifies 
at  — 1°.  Sp.  gr.  0.985  at  12°.  The  aqueous  acid  is  a  colorless  liquid, 
highly  acid  and  corrosive,  and  having  a  penetrating  odor.  Great 
care  must  be  exercised  that  neither  the  solution  nor  the  gas  comes 
in  contact  with  the  skin,  as  they  produce  painful  ulcers  which  heal 
with  difficulty,  and  also  constitutional  symptoms  which  may  last  for 
days.  The  inhalation  of  air  containing  very  small  quantities  of  HF 
has  caused  permanent  loss  of  voice,  and  in  rare  cases,  death.  When 
the  acid  has  accidentally  come  in  contact  with  the  skin  the  part 
should  be  washed  with  dilute  solution  of  potassium  hydroxide,  and 
the  vesicle  which  forms  should  be  opened. 

Both  the  gaseous  acid  and  its  solution  remove  the  silica  from  glass, 
a  property  utilized  in  etching  upon  that  substance,  the  parts  upon 
which  no  action  is  desired  being  protected  by  a  coating  of  wax.  Dur- 
ing the  process  of  etching  the  HF  attacks  the  silica  and  forms  a 
gaseous  silicon  fluoride: 

Si02-f4HF=SiF4+2H20 

Test. — The  presence  of  fluorine  in  a  compound  is  detected  by  re- 
ducing the  substance  to  powder,  moistening  it  with  sulphuric  acid 
in  a  platinum  crucible,  over  which  is  placed  a  slip  of  glass  prepared 
as  above.  At  the  end  of  half  an  hour  the  wax  is  removed  from  the 
glass,  which  will  be  found  to  be  etched  if  the  substance  examined 
contained  a  fluoride. 

CHLORINE. 

Symbol=Cl — Atomic  weight— 35.5  (International=35A6) — Mo- 
lecular weight=7l—Sp.  0r.=2.4502  A. 

Occurrence. — Only  in  combination,  most  abundantly  in  sodium 
chloride ;  the  chlorides  of  potassium,  calcium,  and  magnesium  are  also 
frequently  found  in  nature. 

Preparation. —  (1)  By  heating  together  manganese  dioxide  and 
hydrochloric  acid: 

Mn02+4HCl=MnCl2+2H20+Cl2 

In  a  modification  of  this  process,  which  permits  of  the  more  easy 
recovery  of  the  manganese  dioxide,  nitric  acid  is  used  along  with 
hydrochloric.  The  reaction  is: 


CHLORINE  75 

'2HCl+2HN03+Mn02=Mn(N03)2+2H204-Cl2 

The  MnO2  and  HN03  are  recovered  by  heating  the  manganese 
nitrate  to  190°  and  treating  the  vapor  with  air  and  steam.  The 
reactions  are : 

Mn(N03)2=Mn02+N204  and 
N204-[-H20+0=2HN03 

(2)  By  the  action  of  manganese  dioxide  upon  hydrochloric  acid 
in  the  presence  of  sulphuric  acid,  manganous  sulphate  being  also 
formed : 

Mn02+2HCl+H2S04=MnS04+2H20+Cl2 

The  same  quantity  of  chlorine  is  obtained  as  in  (1),  with  the  use 
of  half  the  amount  of  hydrochloric  acid. 

(3)  By  heating  a  mixture  of  one  part  each  of  manganese  dioxide 
and  sodium  chloride,  with  three  parts  of  sulphuric  acid.     Hydro- 
chloric acid  and  sodium  sulphate  are  first  formed: 

H2S04+2NaCl=:Na2S04+2HCl ; 

and  the  acid  is  immediately  decomposed  by  either  of  the  reactions 
indicated  in  (1)  and  (2),  according  as  sulphuric  acid  is  or  is  not 
present  in  excess. 

(4)  By  the  action  of  potassium  dichromate  upon  hydrochloric 
acid;  potassium  and  chromic  chlorides  being  also  formed: 

K2Cr207+14HCl=2KCl+2CrCl3+7H20+3Cl2 

(5)  In  Deacon's  process  cupric  oxide  is  used  as  a  "contact  sub- 
stance" to  oxidize  hydrochloric  acid.     The  reactions  are: 

2CuCl2=2CuCl+Cl2,  then, 

2CuCl+02=2CuO+Clo,  and,  finally, 

2CuO+4HCl=2CuCl2+2H20 

As  the  0  is  derived  from  air  the  Cl  obtained  is  largely  diluted 
with  N. 

Properties. — Physical. — It  is  about  21/£  times  heavier  than  air; 
it  is  a  greenish  yellow  gas,  at  the  ordinary  temperature  and  pressure; 
it  has  a  penetrating  odor,  and  is,  even  when  highly  diluted,  very 
irritating  to  the  respiratory  passages.  Being  soluble  in  H20  to  the 
extent  of  one  volume  to  three  volumes  of  the  solvent,  it  must  be 
collected  by  displacement  of  air.  An  aqueous  solution  containing, 
when  freshly  made,  a  mixture  of  chlorine  and  oxides  of  chlorine, 
equivalent  to  about  0.35  gm.  of  available  chlorine  in  each  100  cc.  of 
the  solution  is  known  as  chlorine  water,  and  is  official  in  the  U.  S.  P. 
as  Liquor  chlori  compositus.  It  should  bleach,  but  not  redden, 
litmus  paper.  Under  a  pressure  of  6  atmospheres  at  0°,  or  Sl/2 
atmospheres  at  12°,  Cl  becomes  an  oily,  yellow  liquid,  of  sp.  gr.  1.33; 
and  boiling  at  — 33.6°.  Liquid  chlorine,  transported  in  lead-lined 
steel  cylinders,  is  now  an  article  of  commerce. 


76  TEXT-BOOK   OF   CHEMISTRY 

Chemical. — Chlorine  exhibits  a  great  tendency  to  combine  with 
other  elements,  with  all  of  which,  except  F,  0,  N,  and  C,  it  unites 
directly,  frequently  with  evolution  of  light  as  well  as  heat,  and 
sometimes  with  an  explosion.  With  H  it  combines  slowly,  to  form 
hydrochloric  acid,  under  the  influence  of  diffuse  daylight,  and  vio- 
lently in  direct  sunlight,  or  in  highly  actinic  artificial  lights.  A 
candle  burns  in  Cl  with  a  faint  flame  and  thick  smoke,  its  H  com- 
bining with  the  Cl,  while  carbon  becomes  free. 

At  a  red  heat  Cl  decomposes  H20  rapidly,  with  formation  of 
hydrochloric,  chloric,  and  probably  hypochlorous  acids.  The  same 
change  takes  place  slowly  under  the  influence  of  sunlight,  hence 
chlorine  water  should  be  kept  in  the  dark  or  in  bottles  of  yellow 


In  the  presence  of  H,0,  chlorine  is  an  active  bleaching  and  dis- 
infecting agent.  It  acts  as  an  indirect  oxidant,  decomposing  H20, 
the  nascent  0  from  which  then  attacks  the  coloring  or  odorous 
principle : 

H20+C12=2HC1+0 

Chlorine  is  readily  fixed  by  many  organic  substances,  either  by  addition 
or  substitution.  In  the  first  instance,  as  when  Cl  and  olefiant  gas  unite  to 
form  ethylene  chloride,  the  organic  substance  simply  takes  up  two  or  more 
atoms  of  chlorine:  C2H4-|-C12=C2H4C12.  In  the  second  instance,  as  when  Cl 
acts  upon  marsh  gas  to  produce  methyl  chloride:  CH4-(-Cl2=CH3Cl-(-HCl,  each 
substituted  atom  of  Cl  displaces  an  atom  of  H,  which  combines  with  another 
Cl  atom  to  form  hydrochloric  acid. 

Hydrogen  Chloride  —  Hydrochloric  Acid  —  Muriatic  Acid  — 
Acidum  Hydrochloricum  (U.  S.  P.) — HC1 — Molecular  weight= 
36.5— Sp.  gr.  1.259  A. 

Occurrence. — In  volcanic  gases  and  in  the  gastric  juice  of  the 
mammalia. 

Preparation. —  (1)  By  the  direct  union  of  its  constituent  elements. 

(2)  By  the  action  of  sulphuric  acid  upon  a  chloride,  a  sulphate 
being  at  the  same  time  formed: 

H2S04+2NaCl=Na2S04+2HCl 

This  is  the  reaction  by  which  HC1  used  in  the  arts  is  produced. 

(3)  Hydrochloric  acid  is  also  formed  in  a  great  number  of  re- 
actions, as  when  Cl  is  substituted  in  an  organic  compound. 

Properties. — Physical. — A  colorless  gas,  acid  in  reaction  and  taste, 
having  a  sharp,  penetrating  odor,  and  producing  great  irritation  when 
inhaled.  It  becomes  liquid  under  a  pressure  of  40  atmospheres  at  4°. 
Its  critical  temperature  is  52  °  and  its  critical  pressure  83  atmospheres. 
It  is  very  soluble  in  H20,  one  volume  of  which  dissolves  480  volumes 
of  the  gas  at  0°. 

Chemical — Hydrochloric  acid  is  neither  combustible  nor  a  sup- 


CHLORINE  77 

porter  of  combustion,  although  certain  elements,  such  as  K  and  Na, 
burn  in  it.  It  forms  white  clouds  on  contact  with  moist  air. 

Solution  of  Hydrochloric  Acid. — It  is  in  the  form  of  aqueous 
solution  that  this  acid  is  usually  employed  in  the  arts  and  in  phar- 
macy. It  is,  when  pure,  a  colorless  liquid  (yellow  when  impure), 
acid  in  taste  and  reaction,  whose  sp.  gr.  and  boiling-point  vary 
with  the  degree  of  concentration.  When  heated,  it  evolves  HC1, 
if  it  contain  more  than  20  per  cent,  of  that  gas,  and  H20  if  it  con- 
tain less.  A  solution  containing  20  per  cent,  boils  at  111°,  is  of  sp. 
gr.  1.099,  has  the  composition  HC1+8H20,  and  distils  unchanged. 

Commercial  muriatic  acid  is  a  yellow  liquid ;  sp.  gr.  about  1.16 ; 
contains  32  per  cent.  HC1 ;  and  contains  ferric  chloride,  sodium 
chloride,  and  arsenical  compounds. 

Acidum  hydrochloricum  is  a  colorless  liquid,  containing  small 
quantities  of  impurities.  It  contains  not  less  than  31  per  cent,  nor 
more  than  33  per  cent.  HC1  and  its  sp.  gr.  is  about  1.155  at  25  °C. 
(U.  S.  P.)  The  dilute  acid  is  the  above  diluted  with  water.  Sp.  gr. 
1.049=not  less  than  9.5  per  cent,  nor  more  than  10.5  per  cent.  HC1 
(U.  S.  P.). 

C.  P.  (chemically  pure}  acid  is  usually  the  same  as  the  strong 
pharmaceutical  acid  and  far  from  pure  (see  below).  The  strongest 
solution  has  a  sp.  gr.  of  1.20  and  contains  40.8  per  cent.  HC1. 

Hydrochloric  acid  is  classed,  along  with  nitric  and  sulphuric  acids, 
as  one  >of  three  strong  mineral  acids.  It  is  decomposed  by  many 
elements,  with  formation  of  a  chloride  and  liberation  of  hydrogen: 

2HCl+Zn=ZnCl2+H2 

With  oxides  and  hydroxides  of  the  metals  it  enters  into  double 
decomposition,  forming  H20  and  a  chloride: 

CaO+2HCl=CaCl2+H20  or 
Ca(OH)2+2HCl=CaCl2+2H20 

Oxidizing  agents  decompose  HC1  with  liberation  of  Cl.  A  mix- 
ture of  hydrochloric  and  nitric  acids  in  the  proportion  of  three 
molecules  of  the  former  to  one  of  the  latter  (18  cc.  HN03:  82  cc. 
HC1  soln.),  is  the  acidum  nitrohydrochloricum  (nitrohydrochloric 
acid,  nitromuriatic  acid)  of  the  U.  S.  P.,  or  aqua  regia  (see  p.  102). 
The  latter  name  alludes  to  its  power  of  dissolving  gold,  by  combina- 
tion of  the  nascent  Cl,  which  it  liberates,  with  that  metal,  to  form 
the  soluble  auric  chloride  (p.  129).  The  U.  S.  P.  also  includes 
acidum  nitrohydrochloricum  dilutum  (diluted  nitrohydrochloric  acid, 
diluted  nitromuriatic  acid),  which  contains  10  cc.  HN03;  45.5  cc. 
HC1;  and  194.5  cc.  H20. 

Impurities. — A  chemically  pure  solution  of  this  acid  is  exceedingly  rare. 
The  impurities  usually  present  are:  Sulphurous  acid — hydrogen  sulphide  is  given 
off  when  the  acid  is  poured  upon  zinc;  Sulphuric  acid — a  white  precipitate  is 


78  TEXT-BOOK    OF    CHEMISTRY 

formed  with  barium  chloride;  Chlorine  colors  the  acid  yellow;  Lead  gives  a 
black  color  when  the  acid  is  treated  with  hydrogen  sulphide;  Iron — the  acid 
gives  a  red  color  with  ammonium  thiotyanate;  Arsenic — the  method  of  testing 
by  hydrogen  sulphide  is  not  sufficient.  If  the  acid  is  to  be  used  for  toxicological 
analysis,  a  litre,  diluted  with  half  as  much  H2O,  and  to  which  a  small  quantity 
of  potassium  chlorate  has  been  added,  is  evaporated  over  the  water  bath  to 
400  cc. ;  25  cc.  of  sulphuric  acid  are  then  added,  and  the  evaporation  continued 
until  the  liquid  measures  about  100  cc.  This  is  introduced  into  a  Marsh  appara- 
tus and  must  produce  no  mirror  during  an  hour. 

Chlorides. — A  few  of  the  chlorides  are  liquid,  SnCl4,  SbCl5;  the 
remainder  are  solid,  crystalline  and  more  or  less  volatile.  The  me- 
tallic chlorides  are  soluble  in  water,  except  AgCl  and  HgCl,  which 
are  insoluble,  and  PbCl2,  and  CuCl,  which  are  sparingly  soluble. 
The  chlorides  of  the  non-metals  are  decomposed  by  H20. 

The  chlorides  are  formed:  (1)  By  direct  union  of  the  elements: 
P+C15=PC15; 

(2)  By  the  action  of  chlorine  upon  a  heated  mixture  of  oxide 
and  carbon: 

A1203+3C+3C12=A12C16+3CO ; 

(3)  By  solution  of  the  metal,  oxide,  hydroxide,  or  carbonate  in 
HC1: 

Zn+2HCl=ZnCl2+H2 

(4)  By  double  decomposition  between  a  solution  of  a  chloride 
and  that  of  another  salt  whose  metal  forms  an  insoluble  chloride: 

AgN03+NaCl=AgCl+NaN03 

Chloridion — Analytical  Characters. — Solutions  of  hydrochloric 
acid  and  of  chlorides  contain  the  ion,  chloridion  CT,  which  gives  the 
following  reactions:  (1)  With  AgNO3  a  white,  flocculent  ppt.,  insol. 
in  HN03,  sol.  in  NH4OH.  (2)  With  HgNO3,  a  white  ppt.,  which 
turns  black  with  NH4OH. 

Toxicology. — Poisons  and  Corrosives — A  poison  is  any  substance 
which,  being  in  solution  in,  or  acting  chemically  upon  the  blood,  may  pro- 
duce death  or  serious  bodily  harm. 

A  corrosive  is  a  substance  capable  of  producing  death  by  its  chemical 
action  upon  a  tissue  with  which  it  comes  in  direct  contact- 

The  corrosives  act  much  more  energetically  when  concentrated  than  when 
dilute;  and  when  the  dilution  is  great  they  have  no  deleterious  action.  The 
degree  of  concentration  in  which  the  true  poisons  are  taken  is  of  little  influence 
upon  their  action. 

Under  the  above  definitions  the  strong  mineral  acids  act  as  corrosives  rather 
than  as  poisons.  They  produce  their  injurious  results  by  destroying  tissues 
with  which  they  come  in  contact,  and  will  cause  death  as  surely  by  destroying 
a  large  surface  of  skin  as  when  they  are  taken  into  the  stomach. 

The  symptoms  of  corrosion  by  the  mineral  acids  begin  immediately,  during 
the  act  of  swallowing.  The  chemical  action  of  the  acid  upon  every  part  with 
which  it  comes  in  contact  causes  acute  burning  pain,  extending  from  the  mouth 


CHLORINE  79 

to  the  stomach  and  intestine,  referred  chiefly  to  the  epigastrium.  Violent  and 
distressing  vomiting  of  dark,  tarry,  or  "coffee-ground,"  highly  acid  material  is 
a  prominent  symptom.  Eschars,  at  first  white  or  gray,  later  brown  or  black,  are 
formed  where  the  acid  has  come  in  contact  with  the  skin  or  mucous  membrane. 
Respiration  is  labored  and  painful,  partly  by  pressure  of  the  abdominal  mus- 
cles, but  also,  in  the  case  of  hydrochloric  acid,  from  entrance  of  the  irritating 
gas  into  the  respiratory  passages.  Death  may  occur  within  twenty-four  hours, 
from  collapse;  more  suddenly  from  perforation  of  large  blood-vessels,  or  from 
peritonitis;  or  after  several  weeks,  secondarily,  from  starvation,  due  to  closure 
of  the  pylorus  by  inflammatory  thickening,  and  destruction  of  the  gastric  glands. 
The  object  of  the  treatment  in  corrosion  by  the  mineral  acids  is  to  neutralize 
the  acid  and  convert  it  into  a  harmless  salt.  For  this  purpose  the  best  agent  is 
calcined  magnesia,  suspended  in  a  small  quantity  of  water,  or  if  this  is  not  at 
hand,  a  strong  solution  of  soap.  Chalk  and  the  carbonates  and  bicarbonates  of 
sodium  and  potassium  should  not  be  given,  as  they  generate  large  volumes  of  gas. 
The  scrapings  of  a  plastered  wall,  or  oil,  are  entirely  useless.  Any  attempt 
at  the  introduction  of  a  tube  into  the  esophagus  is  attended  with  danger  of 
perforation,  except  in  the  earliest  stages  of  the  intoxication. 

Compounds  of  Chlorine  and  Oxygen. — Two  compounds  of 
chlorine  and  oxygen  are  known.  They  are  both  very  unstable,  and 
prone  to  sudden  violent  decomposition. 

Chlorine  Monoxide. — C120 — 87 — HypoMorous  anhydride,  is 
formed  by  the  action,  below  20  °,  of  dry  Cl  upon  precipitated  mercuric 
oxide:  HgO~t-2Cl2=HgCl2+Cl20. 

On  contact  with  H,0  it  forms  hypochlorous  acid,  HC10,  which 
owing  to  its  instability,  is  not  used  industrially,  although  the  hypo- 
chlorites  of  Ca,  K,  and  Na  are. 

Chlorine  Tetroxide. — Chlorine  peroxide,  C1204 — 135 — is  a  vio- 
lently explosive  body,  produced  by  the  action,  of  sulphuric  acid  upon 
potassium  chlorate.  Below  — 20  °  it  is  an  orange-colored  liquid,  above 
that  temperature  a  yellow  gas.  It  explodes  violently  when  heated 
to  a  temperature  below  100°.  There  is  no  corresponding  hydrate 
known,  and  if  it  be  brought  in  contact  with  an  alkaline  hydroxide, 
a  mixture  of  chlorate  and  chloride  is  formed. 

Besides  the  above,  two  oxy acids  of  Cl  are  known,  the  anhydrides 
corresponding  to  which  have  not  been  isolated. 

Chloric  Acid — HC103 — 84.5 — obtained,  in  aqueous  solution,  as  a 
strongly  acid,  yellowish,  syrupy  liquid,  by  decomposing  barium 
chlorate  by  sulphuric  acid: 

Ba(C103)2+H2S04=BaS04+2HC103 

Perchloric  Acid. — HC104 — 100.5 — is  the  most  stable  of  the  series. 
It  is  obtained  by  boiling  potassium  chlorate  with  hydrofluosilicic 
acid,  decanting  the  cold  fluid,  evaporating  until  white  fumes  appear, 
decanting  from  time  to  time,  and  finally  distilling.  It  is  a  colorless, 
oily  liquid;  sp.  gr.  1.782;  which  explodes  on  contact  with  organic 
substances  or  charcoal. 


80  TEXT-BOOK   OF    CHEMISTRY 

BROMINE. 

Symbol= :Br. — Atomic  weight—^ — (International— :79.92) — Mo- 
lecular weight— \^Q — Sp.  gr.  of  liquid=3.1812  at  0°;  of  vapor— 
5.52  A. 

Occurrence. — Only  in  combination,  most  abundantly  with  Na, 
K,  Ca,  and  Mg  in  sea  water  and  the  waters  of  mineral  springs. 

Preparation. — It  is  obtained  from  the  mother  liquors,  left  by  the 
evaporation  of  sea  water,  and  of  that  of  certain  mineral  springs,  and 
from  sea  weed. 

Bromine  may  be  prepared  from  the  bromide  of  Na  or  K  by  heating 
with  sulphuric  acid  and  manganese  dioxide: 

2KBr+3H2S04+Mn02=2KHS04+MnS04+2H20+Br2 

Properties. — Physical. — A  dark  reddish-brown  liquid,  volatile  at 
all  temperatures  above  — 24.5  ° ;  giving  off  brown-red  vapors  which 
produce  great  irritation  when  inhaled.  Soluble  in  water  to  the  ex- 
tent of  3.2  parts  per  100  at  15°;  more  soluble  in  alcohol,  carbon 
disulphide,  chloroform,  and  ether. 

Chemical. — The  chemical  characters  of  Br  are  similar  to  those 
of  Cl,  but  less  active. — With  H.,0  it  forms  a  crystalline  hydrate  at 
0°  (32°  F):  Br5H20.  Its  aqueous  solution  is  decomposed  by  ex- 
posure to  light,  with  formation  of  hydrobromic  acid. 

It  is  highly  poisonous. 

Hydrogen  Bromide  —  Hydrobromic  acid.  =  HBr  —  Molecular 
weight=8l.  Sp.  gr.  2.71  A. 

Preparation. — This  substance  cannot  be  obtained  from  a  bromide 
as  HC1  is  obtained  from  a  chloride.  It  is  produced,  along  with 
phosphorous  acid,  by  the  action  of  H20  upon  phosphorus  tribromide : 

PBr3+3H20=H3P03+3HBr ; 

or  by  the  action  of  Br  upon  paraffin. 

Properties. — A  colorless  gas;  produces  white  fumes  with  moist 
air;  acid  in  taste  and  reaction,  and  readily  soluble  in  H20,  with 
which  it  forms  a  hydrate,  HBr2H20.  Its  chemical  properties  are 
similar  to  those  of  HC1. 

The  Acidum  hydrobromicum  dilutum  of  the  U.  S.  P.  (dilute 
hydrobromic  acid)  contains  not  less  than  9.5  per  cent,  nor  more  than 
10.5  per  cent,  of  HBr. 

Bromides  closely  resemble  the  chlorides  and  are  formed  under 
similar  conditions.  They  are  decomposed  by  chlorine,  with  forma- 
tion of  a  chloride  and  liberation  of  Br: 

2KBr+Cl2=2KCl+Brt. 
The  metallic  bromides  arc  soluble  in  H20,  except  AgBr  and  HgBr, 


IODINE  81 

which  are  insoluble,  and  PbBr2,  which  is  sparingly  soluble.  The 
bromides  of  Mg,  Al,  Ca  are  decomposed  into  oxide  and  HBr  on 
evaporation  of  their  aqueous  solutions. 

Bromidion — Analytical  Characters. — Solutions  of  hydrobromic 
acid  and  of  bromides  contain  the  anion  Br',  which  gives  the  follow- 
ing reactions:  (1)  With  AgNO;?,  a  yellowish  white  ppt.,  insoluble  in 
HN03,  sparingly  soluble  in  NH4OH.  (2)  With  chlorine  water  a 
yellow  solution  which  communicates  the  same  color  to  chloroform  and 
to  starch-paste. 

Hypobromous  Acid — HBrO 97 — is  obtained,  in  aqueous  solution,  by 

the  action  of  Br  upon  mercuric  oxide,  silver  oxide,  or  silver  nitrate.  When 
Br  is  added  to  concentrated  solution  of  potassium  hydroxide  no  hypobromite  is 
formed,  but  a  mixture  of  bromate  and  bromide,  having  no  decolorizing  action. 
With  sodium  hydroxide,  however,  sodium  hypobromite  is  formed  in  solution; 
and  such  a  solution,  freshly  prepared,  is  used  in  Knop's  process  for  determining 
urea. 

IODINE. 

lodum  (U.  S.  P.) — Symbol=l — Atomic  weight— 127  (Interna- 
tamaZ=126.92).  Molecular  weight— 254:— S  p.  gr.  of  soZwZ=4.948; 
of  vapor=S.116  A. 

Occurrence. — In  combination  with  Na,  K,  Ca,  and  Mg,  in  sea- 
water,  the  waters  of  mineral  springs,  marine  plants  and  animals. 
Cod-liver  oil  contains  about  37  parts  in  100,000. 

Preparation. — It  is  obtained  from  the  ashes  of  sea-weed,  called 
kelp  or  varech.  These  are  extracted  with  H20,  and  the  solution 
evaporated  to  small  bulk.  The  mother  liquor,  when  separated  from 
the  other  salts  which  crystallize  out,  contains  the  iodides,  which  are 
decomposed  by  Cl,  aided  by  heat,  and  the  liberated  iodine  is  con- 
densed. 

Iodine  may  be  prepared  from  the  iodide  of  Na  or  K  by  heating 
with  sulphuric  acid  and  manganese  dioxide: 

2KI+3H2S04+Mn02=2KHS04+MnS04+2H20+I2 

Properties. — Physical. — Blue-gray,  crystalline  scales,  having  a 
metallic  luster.  Volatile  at  all  temperatures,  the  vapor  having  a  violet 
color  and  a  peculiar  odor.  The  density  of  vapor  of  iodine,  at 
one  atmosphere  of  pressure  and  at  temperatures  between  its  boiling 
point  and  about  500°  is  254  (0=32),  corresponding  to  the  molecular 
formula  I2,  but  above  that  temperature  the  density  diminishes,  until 
at  1,500°  it  has  fallen  to  127,  corresponding  to  the  molecular  formula 
I,  where  it  remains  constant.  Molecular  iodine  is,  therefore,  dis- 
sociated by  heat.  Iodine  is  very  sparingly  soluble  in  water,  but  the 
aqueous  solution,  standing  over  excess  of  iodine,  continues  to  dis- 
solve it  by  reason  of  the  formation  of  hydriodic  acid.  Solutions  of 
hydriodic  acid  and  of  metallic  iodides  dissolve  notably  larger  quan- 
tities of  iodine  than  does  pure  water,  probably  because  of  the  forma- 


82  TEXT-BOOK   OF   CHEMISTRY 

tion  of  the  ion  I3'.  Lugol's  solution — Liquor  iodi  compositus  (U.  S. 
P.) — contains  5  parts  of  iodine  and  10  parts  of  potassium  iodide  in 
100  parts  of  water.  Iodine  is  very  soluble  in  alcohol,  ether,  chloro- 
form, benzene  and  carbon  disulphide.  With  the  three  last  named 
solvents  the  solutions  are  violet,  with  others  brown  in  color. 

Chemical. — In  its  chemical  characters  I  resembles  Cl  and  Br,  but 
is  less  active.  It  decomposes  H20  slowly  and  is  a  weak  bleaching 
and  oxidizing  agent.  In  presence  of  water,  it  decomposes  hydrogen 
sulphide  with  formation  of  hydriodic  acid,  and  liberation  of  sulphur. 
It  does  not  combine  directly  with  oxygen,  but  does  with  ozone. 
Potassium  hydroxide  solution  dissolves  it,  with  formation  of  potas- 
sium iodide,  and  some  hypoiodite.  Nitric  acid  oxidizes  it  to  iodic 
acid.  With  ammonium  hydroxide  solution  it  forms  the  explosive 
nitrogen  iodide. 

Toxicology. — Taken  internally,  iodine  acts  both  as  a  local  irritant  and  as 
a  true  poison.  It  is  discharged  as  an  alkaline  iodide  by  the  urine  and  perspira- 
tion, and  when  taken  in  large  quantity  it  appears  in  the  feces. 

The  poison  should  be  removed  as  rapidly  as  possible  by  the  use  of  the 
stomach  tube  and  of  emetics.  Farinaceous  substances  may  also  be  given. 

Hydrogen  Iodide — Hydriodic  acid — HI — Molecular  weight=128. 

Preparation.— By  the  decomposition  of  phosphorus  triiodide  by 
water : 

PI3+3H20-H3P03+3HI 

Or,  in  solution  by  passing  hydrogen  sulphide  through  water  holding 
iodine  in  suspension: 

H2S+2I2=S2+4HI 

Properties. — A  colorless  gas,  forming  white  fumes  on  contact  with 
air,  and  of  strongly  acid  reaction.  Under  the  influence  of  cold  and 
pressure  it  forms  a  yellow  liquid,  which  solidifies  at  — 55°.  Water 
dissolves  it  to  the  extent  of  425  volumes  for  each  volume  of  the 
solvent  at  10°. 

It  is  partly  decomposed  into  its  elements  by  heat.  Mixed  with  0 
it  is  decomposed,  even  in  the  dark,  with  formation  of  H20  and  libera- 
tion of  I.  Under  the  influence  of  sunlight  the  gas  is  slowly  decom- 
posed, although  its  solutions  are  not  so  affected,  if  they  be  free  from 
air.  Chlorine  and  bromine  decompose  it,  with  liberation  of  iodi  in*. 
With  many  metals  it  forms  iodides.  It  yields  up  its  H  readily  and  is 
used  in  organic  chemistry  as  a  source  of  that  element  in  the  nascent 
state. 

The  Acidum  hydriodicum  dilutum  (diluted  hydriodic  acid)  of  the 
U.  S.  P.  contains  not  less  than  9.5  per  cent,  nor  more  than  10.5 
per  cent,  of  HI. 

Iodides  are  formed  under  the  same  conditions  as  the  chlorides  and 
bromides,  which  they  resemble  in  their  properties.  The  metallic 


SULPHUR   GROUP  83 

iodides  are -soluble  in  water — except  Agl,  Hgl,  which  are  insoluble, 
and  PbI2,  which  is  very  slightly  soluble.  The  iodides  of  the  earth 
metals  are  decomposed  into  oxide  and  HI  on  evaporation  of  their 
aqueous  solutions.  Chlorine  decomposes  the  iodides  as  it  does  the 
bromides. 

lodidion — Analytical  Characters. — Solutions  of  hydriodic  acid  or 
of  iodides  contain  iodidion,  I',  which  forms  a  yellow  ppt.,  insol.  in 
HN03  and  in  NH4OH,  with  Ag'N03.  Brown  solutions  of  excess  of 
iodine  in  HI  or  KI  contain  triodidion,  I3',  which,  as  iodine  is  removed 
from  the  solution,  is  decomposed  into  I'+I2.  Aqueous  or  alcoholic 
solutions  of  free  iodine,  not  of  iodidion,  color  starch  paste  dark  blue 
or  black,  and  chloroform  or  carbon  bisulphide  violet.  The  same  colors 
are  produced  with  solutions  of  iodides  after  liberation  from  them  of 
free  iodine  by  fuming  HN03  or  chlorine  water.  At  about  100°  starch 
iodide  is  dissociated  and  decolorized,  the  color  returning  on  cooling. 

Chlorides  of  Iodine. — Chlorine  and  iodine  combine  with  each  other  in 
two  proportions:  Iodine  monochloride,  or  protochloride — IC1  is  a  red-brown, 
oily,  pungent  liquid,  formed  by  the  action  of  dry  Cl  upon  I,  and  distilling  at 
100°.  Iodine  trichloride,  or  perchloride — IC13  is  a  yellow,  crystalline  solid, 
having  an  astringent,  acid  taste  and  a  penetrating  odor;  very  volatile;  its 
vapor  irritating;  easily  soluble  in  water.  It  is  formed  by  saturating  H2O 
holding  I  in  suspension  with  Cl,  and  adding  concentrated  sulphuric  acid.  IC13 
has  been  used  as  an  antiseptic. 

Oxyacids  of  Iodine. — The  best  known  of  these  are  the  highest  two  of  the 
series — iodic  and  periodic  acids. 

lodic  Acid — HIO3 — 176  is  formed  as  an  iodate,  whenever  I  is  dissolved  in 
a  solution  of  an  alkaline  hydroxide: 

I6-f6KOH=KIO3-f5KI-|-3H20 

As  the  free  acid,  by  the  action  of  strong  oxidizing  agents,  such  as  nitric  acid, 
or  chloric  acid,  upon  I ;  or  by  passing  Cl  for  some  time  through  H2O  holding  I  in 
suspension. 

Iodic  acid  appears  in  white  crystals,  decomposable  at  170°,  and  quite 
soluble  in  H2O,  the  solution  having  an  acid  reaction,  and  a  bitter,  astringent 
taste. 

It  is  an  energetic  oxidizing  agent,  yielding  up  its  O  readily,  with  separa- 
tion of  elementary  I  or  of  HI.  It  is  used  as  a  test  for  the  presence  of  morphine. 

Periodic  Acid — HIO4 — 192 — is  formed  by  the  action  of  Cl  upon  an  alkaline 
solution  of  sodium  iodate.  The  sodium  salt  thus  obtained  is  dissolved  in  nitric 
acid,  treated  with  silver  nitrate,  and  the  resulting  silver  periodate  is  then 
decomposed  with  H2O.  From  the  solution  the  acid  is  obtained  in  colorless 
crystals,  fusible  at  130°,  very  soluble  in  water,  and  readily  decomposable  by  heat. 


II.    SULPHUR  GROUP. 
SULPHUR.     SELENIUM.     TELLURIUM. 

The  elements  of  this  group  are  bivalent  in  most  of  their  com- 
pounds ;  in  some  they  are  quadrivalent  or  hexavalent.  With  hydrogen 
they  form  compounds  composed  of  one  volume  of  the  element,  in  the 


84  TEXT-BOOK   OF   CHEMISTRY 

form  of  vapor,  with  two  volumes  of  hydrogen — the  combination 
being  attended  with  condensation  in  volume  of  one-third.  Mineral 
acids  in  which  they  occur  are  dibasic.  They  are  all  solids  at  ordi- 
nary temperatures.  The  relation  of  their  compounds  to  each  other  is 
shown  in  the  following  table: 

H2S  S02                 SO8  H2S02  H2S04  H2S04 

H2Se  Se02                SeO3  H2SeO3  H2SeO4 

H2Te  Te02               TeO3  H2TeO3  H2TeO4 

Ilydro-ic  acid.  Dioxide.  Trioxide.  Hypo-ous  acid,      -ous  acid.  -ic  acid. 

SULPHUR. 

Symbol=S — Atomic  weight=32  (International=32.Q6) .  Molecu- 
lar weight=64: — Sp.  gr.  of  vapor=2.22  A. 

Occurrence. — Free  in  crystalline  powder,  large  crystals,  or 
amorphous,  in  volcanic  regions.  In  combination  in  sulphides  and  sul- 
phates, and  in  protein  substances. 

Preparation. — By  purification  of  the  native  sulphur  or  decom- 
position of  pyrites,  natural  sulphides  of  iron. 

Crude  sulphur  is  the  product  of  the  first  distillation.  A  second 
distillation,  in  more  perfectly  constructed  apparatus,  yields  refined 
sulphur.  During  the  first  part  of  the  distillation,  while  the  air  of 
the  condensing  chamber  is  still  cool,  the  vapor  of  S  is  suddenly  con- 
densed into  a  fine,  crystalline  powder,  which  is  flowers  of  sulphur, 
sulphur  sublimatum  (sublimed  sulphur)  (U.  S.  P.).  Later,  when 
the  temperature  of  the  condensing  chamber  is  about  114°,  the  liquid  S 
collects  at  the  bottom,  whence  it  is  drawn  off  and  cast  into  sticks  of 
roll  sulphur. 

Properties. — Physical. — Sulphur,  also  known  as  brimstone,  is 
usually  yellow  in  color.  At  low  temperature,  and  in  minute  sub- 
division, as  in  the  precipitated  milk  of  sulphur,  sulphur  praecipitatum 
(U.  S.  P.),  it  is  almost  quite  colorless.  Its  taste  and  odor  are  faint 
but  characteristic.  At  114°  it  fuses  to  a  thin  yellow  liquid,  which  at 
150°-160°  becomes  thick  and  brown;  at  330°-340°  it  again  becomes 
thin  and  light  in  color;  finally  it  boils,  giving  off  brownish  yellow 
vapor  at  a  temperature  variously  stated  between  440°  and  448°. 
If  heated  to  about  400°  and  suddenly  cooled,  it  is  converted  into 
plastic  sulphur,  which  may  be  moulded  into  any  desired  form.  It 
is  insoluble  in  water,  sparingly  soluble  in  aniline,  phenol,  benzene, 
petroleum  ether,  and  chloroform;  readily  soluble  in  sulphur  chloride, 
S2C12,  and  carbon  disulphide.  It  dissolves  in  hot  alcohol,  and  crystal- 
lizes from  the  solution,  on  cooling,  in  white  prismatic  crystals.  It  is 
dimorphous.  When  fused  sulphur  crystallizes  it  does  so  in  oblique 
rhombic  prisms.  Its  solution  in  carbon  disulphide  deposits  it  on 
evaporation  in  rhombic  octahodra.  The  prismatic  variety  is  of  sp. 
gr.  1.95  and  fuses  at  120°;  the  sp.  gr.  of  the  octahedral  is  2.05  and 


SULPHUR  85 

its  fusing  point  114.5°.  The  prismatic  crystals,  by  exposure  to  air, 
become  opaque,  by  reason  of  a  gradual  conversion  into  octahedra. 

Chemical. — Sulphur  unites  readily  with  other  elements,  especially 
at  high  temperatures.  Heated  in  air  or  0,  it  burns  with  a  blue  flame 
to  sulphur  dioxide,  S02.  In  H  it  burns  with  formation  of  hydrogen 
sulphide,  H2S.  The  compounds  of  S  are  similar  in  constitution,  and 
to  some  extent  in  chemical  properties,  to  those  of  0.  In  many  organic 
substances  S  may  replace  0,  as  in  thiocyanic  acid,  CNSH,  correspond- 
ing to  cyanic  acid,  CNOH.  Such  compounds  are  designated  by  the 
syllable  fhio;  the  syllable  sulpho,  in  the  name  of  a  compound,  indi- 
cates that  it  contains  the  bivalent  group,  S02. 

Sulphur  is  used  principally  in  the  manufacture  of  gunpowder; 
also  to  some  extent  in  making  sulphuric  acid,  sulphur  dioxide,  and 
matches,  and  for  the  prevention  of  fungoid  and  parasitic  growths. 

Hydrogen  Sulphide  —  sulphuretted  hydrogen  —  Sulphydric 
acid — H2S — Molecular  weig7ii=34: — Sp.  #r.=1.19  A. 

Occurrence. — In  volcanic  gases ;  as  a  product  of  the  decomposition 
of  organic  substances  containing  S;  in  solution,  in  the  waters  of 
some  mineral  springs;  and,  occasionally,  in  small  quantity,  in  the 
gases  of  the  intestine.  It  is  produced  from  proteins  and  other 
organic  substances  containing  S  by  microbic  action  (sulphydric 
fermentation). 

Preparation. —  (1)  By  direct  union  of  the  elements;  either  by 
burning  S  an  II,  or  by  passing  H  through  molj^ri  S. 

(2)  By  the   action   of  nascent   H   upon  sulphuric   acid,   if  the 
mixture  become  heated.     (See  Marsh  test  for  arsenic.) 

(3)  By  the  action  of  HC1  upon  antimony  trisulphide: 

Sb2S3+6HCl=2SbCl3+3H2S 

(4)  By  the  action  of  dilute  sulphuric  acid  upon  ferrous  sulphide: 

FeS+H2S04=FeS04+H2S 

This  is  the  method  generally  used. 

(5)  By  the  action  of  HC1  upon  calcium  sulphide: 

CaS+2HCl=CaCl2+H2S 

Properties. — Physical. — A  colorless  gas  having  the  odor  of  rotten 
eggs  and  a  disgusting  taste;  soluble  in  H20  to  the  extent  of  3.23 
parts  to  1  at  15  ° ;  soluble  in  alcohol.  Under  17  atmospheres  pressure, 
or  at  —74°  at  the  ordinary  pressure,  it  liquefies;  at  — 85.5°  it  forms 
white  crystals. 

Chemical. — Burns  in  air  with  formation  of  sulphur  dioxide  and 
water :  • 

2H2S-f  302=2S02+2H20 


86  TEXT-BOOK   OF   CHEMISTRY 

If  the  supply  of  oxygen  is  deficient,  H20  is  formed,  and  sulphur 
liberated :  2H2S+02=:2H20+S2 

Mixtures  of  H2S  and  air  or  0  explode  on  contact  with  flame. 
Solutions  of  the  gas  when  exposed  to  air  become  oxidized  with  de- 
position of  S.  Such  solutions  should  be  made  with  boiled  H20,  and 
kept  in  bottles  which  are  completely  filled,  and  well  corked.  Oxidizing 
agents,  Cl,  Br,  and  I  remove  its  H  with  deposition  of  S.  Hydrogen 
sulphide  and  sulphur  dioxide  mutually  decompose  each  other  into 
water,  pentathionic  acid  and  sulphur: 

4S02+3H2S=2H20+H2S506+S2 

When  the  gas  is  passed  through  a  solution  of  an  alkaline  hy- 
droxide its  S  displaces  the  0  of  the  hydroxide  to  form  a  sulphydrate : 

H2S+KOH=H20+KHS 

With  solutions  of  metallic  salts  H2S  usually  relinquishes  its  S 
to  the  metal : 

CuS04+H2S=CuS+H2S04 

a  property  which  renders  it  of  great  value  in  analytical  chemistry. 
Physiological. — Hydrogen  sulphide  is  produced  in  the  intestine 


FIG.  12. 

by  the  decomposition  of  protein  substances  or  of  taurochloric  acid; 
it  also  occurs  sometimes  in  abscesses,  and  in  the  urine  in  tuberculosis, 
variola,  and  cancer  of  the  bladder.  It  may  also  reach  the  bladder 
by  diffusion  from  the  rectum. 

Toxicology. — An  animal  dies  almost  immediately  in  an  atmosphere  of  pure 
H2S,  and  the  diluted  gas  is  still  rapidly  fatal.  An  atmosphere  containing  1  per 
cent,  may  be  fatal  to  man,  although  individuals  habituated  to  its  presence  can 
exist  in  an  atmosphere  containing  3  per  cent.  Its  toxic  powers  are  due  pri- 
marily, if  not  entirely,  to  its  power  of  reducing  and  combining  with  the  blood- 
coloring  matter. 

The  form  in  which  hydrogen  sulphide  generally  produces  deleterious  effects 
is  as  a  constituent  of  the  gases  emanating  from  sewers,  privies,  burial  vaults, 
etc.  These  give  rise  to  either  slow  poisoning,  as  when  sewer  gases  are  admitted 
to  sleeping  and  other  apartments  by  defective  plumbing,  or  to  sudden  poisoning, 
as  when  a  person  enters  a  vault  or  other  locality  containing  the  noxious 
atmosphere. 

The  treatment  should  consist  in  promoting  the  inhalation  of  pure  air,  arti- 
ficial respiration,  cold  affusions,  and  the  administration  of  stimulants. 

After  death  the  blood  is  found  to  be  dark  in  color,  and  gives  the  spectrum 
shown  in  Fig.  12,  due  to  sulphemoglobin. 


SULPHUR 


87 


Sulphides  and  Hydrosulphides.  —  These  compounds  bear  the  same 
relation  to  sulphur  that  the  oxides  and  hydroxides  do  to  oxygen.  The 
two  sulphides  of  arsenic,  As2S3  and  As2S5,  correspond  to  the  two 
oxides,  As203  and  As205,  and  the  potassium  hydrosulphide,  KHS, 
corresponds  to  the  hydroxide,  KOH. 

Many  metallic  sulphides  occur  in  nature,  and  are  important  ores 
of  the  metals,  as  the  sulphide  of  zinc,  mercury,  cobalt,  nickel,  and 
iron.  They  are  formed  artificially,  either  by  direct  union  of  the  ele- 
ments at  elevated  temperatures,  as  in  the  case  of  iron:  Fe-f-S=FeS; 
or  by  reduction  of  the  corresponding  sulphate,  as  in  the  case  of 
calcium  : 

CaS04+2C=CaS+2C02 

The  sulphides  are  insoluble  in  H20,  except  those  of  the  alkali 
metals.  Many  of  the  sulphides  are  soluble  in  alkaline  liquids,  and 
behave  as  thio-anhydrides,  forming  thio-salts,  corresponding  to  the 
oxysalts.  Thus  potassium  arsenate,  K3As04,  and  thioarsenate, 
K3AsS4;  antimonate,  K3Sb04,  and  thioantimonate,  K3SbS4. 

The  metallic  sulphides  are  decomposed  when  heated  in  air,  usually 
with  the  formation  of  sulphur  dioxide  and  the  metallic  oxide  ;  some- 
times with  the  formation  of  the  sulphate;  and  sometimes  with  the 
liberation  of  the  metal,  and  the  formation  of  sulphur  dioxide.  The 
strong  mineral  acids  decompose  the  sulphides  with  the  formation  of 
hydrogen  monosulphide. 

Analytical  Characters.  —  Hydrogen  Sulphide.  —  (1)  Blackens 
paper  moistened  with  lead  acetate  solution.  (2)  Has  an  odor  of 
rotten  eggs. 

Sulphides.  —  (1)  Heated  in  the  oxidizing  flame  of  the  blowpipe, 
give  a  blue  flame  and  odor  of  S02.  (2)  With  a  mineral  acid  give 
off  H2S  (except  sulphides  of  Hg,  Au,  and  Pt). 

Sulphur  Dioxide.  —  Sulphurous  oxide,  or  anhydride  —  S02  —  Mo- 
lecular weight=64:  —  Sp.  gr.  of  gas=2.2l3  ;  of  liquid=lA5. 


Occurrence.  —  In  volcanic  gases  and  in  solution  in  some  mineral 
waters. 

Preparation.  —  (1)  By  burning  S  in  air  or  0. 

(2)  By  roasting  iron  pyrites  in  a  current  of  air. 

(3)  By  heating  sulphuric  acid  with  copper: 

2H2S04+Cu=CuS04+2H20+S02 

(4)  By  heating  sulphuric  acid  with  charcoal: 

2H2S04+C=2S02+C02+2H20 

When  the  gas  is  to  be  used  as  a  disinfectant  it  is  usually  obtained 
by  reaction  (1)  ;  in  sulphuric  acid  factories  (2)  is  used;  in  the 
laboratory  (3)  is  used. 


88  TEXT-BOOK   OF   CHEMISTRY 

Properties. — Physical. — A  colorless,  suffocating  gas,  having  a 
disagreeable  and  persistent  taste.  Very  soluble  in  H20,  which  at  15° 
dissolves  about  40  times  its  volume  (see  below)  ;  also  soluble  in 
alcohol.  At  — 10°  it  forms  a  colorless,  mobile,  transparent  liquid,  by 
whose  rapid  evaporation  a  cold  of  — 65°  is  obtained.  Liquid  S02 
packed  in  sealed  tins  or  in  siphons,  is  now  a  commercial  article. 

Chemical. — Sulphur  dioxide  is  neither  combustible  nor  a  supporter 
of  combustion.  Heated  with  H  it  ijs  decomposed: 

S02+2H2=S+2H20 

With  nascent  hydrogen,  H2S  is  formed : 

S02+3H2=H2S+2H,0 

Water  not  only  dissolves  the  gas,  but  combines  with  it  to  form 
the  true  sulphurous  acid,  H->S03.  With  solutions  of  metallic  hydrox- 
ides it  forms  metallic  sulphites:  S02+KOH=KHS03 ;  or  S02-f 
2KOH=K2S03+H20.  A  hydrate  having  the  composition  H2S03, 
8H20  has  been  obtained  as  a  crystalline  solid,  fusible  at  -(-4°. 

Sulphur  dioxide  and  sulphurous  acid  solution  are  powerful  re- 
ducing agents,  being  themselves  oxidized  to  sulphuric  acid:  S02+ 
H20=H2S04;  or  H2SO3+0=H2S04.  It  reduces  nitric  acid  with 
formation  of  sulphuric  acid  and  nitrogen  tetroxide:  S02-|-2HN03= 
H2S04-{-N204.  It  decolorizes  organic  pigments,  without,  however, 
destroying  the  pigment,  whose  color  may  be  restored  by  an  alkali  or 
a  stronger  acid.  It  destroys  H2S,  acting,  in  this  instance,  not  as  a  re- 
ducing but  as  an  oxidizing  agent:  4S02+3H2S=2H20+H2SBOfl^S2. 
With  Cl  it  combines  directly  under  the  influence  of  sunlight  to  form 
sulphuryl  chloride  (S02)"C12. 

Analytical  Characters. — (1)  Odor  of  burning  sulphur. 

(2)  Paper  moistened  with  starch  paste  and  iodic  acid  solution 
turns  blue  in  air  containing  1  in  3,000  of  S02. 

Sulphur  Trioxide. — Sulphuric  oxide  or  anhydride — S03 — Molecu- 
lar weight=80—Sp.  gr.  1.95. 

Preparation.— (1)  By  union  of  SO2  and  0  at  250°-300°  or  in 
presence  of  spongy  platinum. 

(2)  By  heating  sulphuric   acid  in  presence  of   phosphoric   an- 
hydride : 

H2S04+P205=SO3+2HP03 

(3)  By  heating  dry  sodium  pyrosulphate : 

Na2S207=Na,SO4+S03 

Properties. — White,  silky,  odorless  crystals  which  give  off  white 
fumes  in  damp  air.  It  unites  with  H20  with  a  hissing  sound,  and 
elevation  of  temperature,  to  form  sulphuric  acid.  When  dry  it  does 
not  redden  litmus. 


SULPHUR  89 

Sulphur  trioxide  exists  in  two  isomeric  (see  isomerism)  modifica- 
tions, being  one  of  the  few  instances  of  isomerism  among  mineral 
substances.  The  a  modification,  liquid  at  summer  temperature, 
solidifies  in  colorless  prisms  at  16°  and  boils  at  46°.  The  ft  isomere 
is  a  white,  crystalline  solid  which  gradually  fuses  and  passes  into  the 
a  form  at  about  50°. 

Oxyacids  of  Sulphur. 

H2S02  Hyposulphurous  acid.  H2S20T  Pyrosulphuric  acid. 

H2S03  Sulphurous  acid-  H2S200  Dithionic  acid. 

H2SO4  Sulphuric  acid.  H2S3Ofl  Trithionic  acid. 

H2S,O8  Persulphuric  acid.  H2S4Oa  Tetrathionic  acid. 

H2Sk03  Thiosulphuric  acid.  H2S506  Pentathionic  acid. 

.  The  graphic  formulae  of  the  chief  of  these  acids  are  appended  : 


o/OH  0  \\oXOH 

b\OH  0//b\OH 

Hyposulphurous    acid.  Sulphuric  acid. 

Q/OH  0\\Q/SH 

^\OH  0//b\OH 

Sulphurous  acid.  Thiosulphuric    acid. 

Hyposulphurous  Acid  —  H2S02  —  66.  —  Hydro  sulphurous  acid  —  Is 
an  unstable  body  known  only  in  solution,  obtained  by  the  action  of 
zinc  upon  solution  of  sulphurous  acid.  It  is  a  powerful  bleaching  and 
deoxidizing  agent. 

Sulphurous  Acid  —  H2S03  —  82.  —  Although  sulphurous  acid  has 
not  been  isolated,  it,  in  all  probability,  exists  in  the  acid  solution, 
formed  when  sulphur  dioxide  is  dissolved  in  water:  S02-[-H20= 
S03H2.  Its  salts,  the  sulphides,  are  well  defined.  From  the  existence 
of  certain  organic  derivatives  (see  sulphonic  acids)  it  would  seem  that 
two  isomeric  modifications  of  the  acid  may  exist.  They  are  distin- 
guished as  the  symmetrical,  in  which  the  S  atom  is  quadrivalent  : 

0_s  /OH 
s  \OH' 

and  the  unsymmetrical,  in  which  the  S  atom  is  hexavalent: 

0\\fi/H 

0//b\OIT 

Sulphites.  —  The  sulphites  are  decomposed  by  the  stronger  acids, 
with  evolution  of  sulphur  dioxide.  Nitric  acid  oxidizes  them  to  sul- 
phates. The  sulphites  of  the  alkali  metals  are  soluble,  and  are  active 
reducing  agents.  N  . 

The  analytical  characters  of  the  sulphites  (sulphosion)  are:  (1) 
With  HC1  they  give  off  S02.  (2)  With  zinc  and  HC1  they  give  off 
H,S.  (3)  With  AgN03  they  form  a  white  ppt.,  soluble  in  excess  of 


90  TEXT-BOOK   OF   CHEMISTRY 

sulphite,  and  depositing  metallic  Ag  when  the  mixture  is  boiled.  (4) 
With  Ba  (N03)2  they  form  a  white  ppt,  soluble  in  HC1.  If  chlorine 
water  is  added  to  the  solution  so  formed  a  white  ppt.,  insoluble  in 
acids,  is  produced. 

Sulphuric  Acid — Oil  of  Vitriol — Acidum  sulphuricum  (U.  S.  P.) 
-H2S04— 98. 

Preparation. — (1)  By  the  union  of  sulphur  trioxide  and  water: 

S03+H20=H2S04. 

(2)  By  the  oxidation  of  S02  or  of  S  in  the  presence  of  water: 
2S02+2H20+02=2H2S04;  or 
S2+2H20+302=2H2S04. 

The  manufacture  of  H2S04  may  be  said  to  be  the  basis  of  all 
chemical  industry,  as  there  are  but  few  processes  in  chemical  tech- 
nology into  some  part  of  which  it  does  not  enter.  The  method  fol- 
lowed at  present,  the  result  of  gradual  improvement,  may  be  divided 
into  two  stages:  (1)  the  formation  of  a  dilute  acid;  (2)  the  con- 
centration of  this  product. 

The  first  part  is  carried  on  in  immense  chambers  of  timber,  lined 
with  lead,  and  furnishes  an  acid  having  a  sp.  gr.  of  1.55,  and  con- 
taining 65  per  cent,  of  true  sulphuric  acid,  H2S04.  Into  these  cham- 
bers S02,  obtained  by  burning  sulphur,  or  by  roasting  pyrites,  is 
driven,  along  with  a  large  excess  of  air.  In  the  chambers  it  comes 
in  contact  with  nitric  acid,  at  the  expense  of  which  it  is  oxidized  to 
H2S04,  while  nitrogen  tetroxide  (red  fumes)  is  formed: 
S02+2HN03=H2S04+N204 

Were  this  the  only  reaction,  the  disposal  of  the  red  fumes  would 
present  a  serious  difficulty  and  the  amount  of  nitric  acid  consumed 
would  be  very  great.  A  second  reaction  occurs  between  the  red 
fumes  and  H20,  which  is  injected  in  the  form  of  steam,  by  which 
nitric  acid  and  nitrogen  dioxide  are  produced : 
3N204+2H20=4HN03+2NO 

The  nitrogen  dioxide  in  turn  combines  with  0  to  produce  the 
tetroxide,  which  then  regenerates  a  further  quantity  of  nitric  acid, 
and  so  on.  This  series  of  reactions  is  made  to  go  on  continuously, 
the  nitric  acid  being  constantly  regenerated,  and  acting  merely  as  a 
carrier  of  0  from  the  air  to  the  S02,  in  such  manner  that  the  sum 
of  the  reactions  may  be  represented  by  the  following  equation : 
2S02+2H20+02=2H2S04 

The  acid  is  allowed  to  collect  in  the  chambers  until  it  has  the  sp. 
gr.  1.55,  when  it  is  drawn  off.  This  chamber  acid,  although  used  in 
a  few  industrial  processes,  is  not  yet  strong  enough  for  most  pur- 
poses. It  is  concentrated,  first,  by  evaporation  in  shallow  leaden 
pans,  until  its  sp.  gr.  reaches  1.746.  At  this  point  it  begins  to  act 


SULPHUR  91 

upon  the  lead,  and  is  transferred  to  platinum  stills,  where  the  con- 
centration is  completed. 

Varieties. — Sulphuric  acid  is  met  with  in  several  conditions  of 
concentration  and  purity: 

(1)  The  commercial  oil  of  vitriol,  largely  used  in  manufacturing 
processes,  is  a  more  or  less  deeply  colored,  oily  liquid,  varying  in  sp. 
gr.  from  1.833  to  1.842,  and  in  concentration  from  93  per  cent,  to 
99V2  per  cent,  of  true  H2S04. 

(2)  C.  P.  acid—Acidum  sulphuricum  (U.  S.  P.),  of  sp.  gr.  1.83 
at  25°,  and  containing  not  less  than  93  per  cent,  nor  more  than  95 
per  cent,  of  H2S04,  is  colorless  and  comparatively  pure  (see  below). 

(3)  Glacial  sulphuric  acid  is  a  hydrate  of  the  composition  H2S04, 
H20,  sometimes  called  bihydrated  sulphuric  acid,  which  crystallizes 
in  rhombic  prisms,  fusible  at  +8.5°  when  an  acid  of  sp.  gr.  1.788 
is  cooled  to  that  temperature. 

(4)  Diluted  sulphuric  acid  (U.  S.  P.)  is  a  dilute  acid  of  sp.  gr. 
1.067  and  containing  9.5  per  cent.  H2S04  (U.  S.  P.). 

(5)  Aromatic  sulphuric  acid  (U.  S.  P.)  contains  not  less  than  19 
per  cent,  and  not  more  than  21  per  cent,  of  H2S04. 

Properties. — Physical. — A  colorless,  heavy,  oily  liquid;  sp.  gr. 
1.842  at  12°;  crystallizes  at  10.5°;  boils  at  338°.  It  is  odorless, 
intensely  acid  in  taste  and  reaction,  and  highly  corrosive.  It  is  non- 
volatile at  ordinary  temperatures.  Mixtures  of  the  acid  with  H20 
have  a  lower  boiling  point,  and  lower  sp.  gr.  as  the  proportion  of 
H20  increases. 

Chemical. — At  a  red  heat  vapor  of  H2S04  is  partly  dissociated 
into  S03  and  H20;  or,  in  the  presence  of  platinum,  into  S02,  H20 
and  0.  When  heated  with  S,  C,  P,  Hg,  Cu,  or  Ag,  it  is  reduced 
with  formation  of  S02. 

Sulphuric  acid  has  a  great  tendency  to  absorb  H20,  the  union 
being  attended  with  elevation  of  temperature,  increase  of  bulk,  and 
diminution  of  sp.  gr.  of  the  acid,  and  contraction  of  volume  of  the 
mixture.  Three  parts,  by  weight,  of  acid  of  sp.  gr.  1.842,  when  mixed 
with  one  part  of  H20  produce  an  elevation  of  temperature  to  130° 
and  the  resulting  mixture  occupies  a  volume  1-6  less  than  the  sum 
of  the  volumes  of  the  constituents.  Strong  H2S04  is  a  good  desiccator 
of  air  or  gases.  It  should  not  be  left  exposed  in  uncovered  vessels, 
lest  by  increase  of  volume  it  overflow.  It  is  by  virtue  of  its  affinity 
for  H20  that  H2S04  chars  or  dehydrates  organic  substances.  Sul- 
phuric acid  is  a  powerful  dibasic  acid. 

The  commercial  acid  is  very  impure.  The  colorless  so-called  C.  P. 
acid  may  also  contain:  PbS04,  which  forms  a  black  ppt.  when  the 
dilute  acid  is  treated  with  H2S;  S02,  which  gives  off  H2S  when  the 
dilute  acid  is  added  to  Zn ;  As,  which  appears  as  a  mirror  when  the 
dilute  acid  is  examined  by  Marsh's  test;  oxides  of  nitrogen,  which 
communicate  a  red  or  pink  color  to  pure  brucine. 


92  TEXT-BOOK    OF    CHEMISTRY 

Sulphates. — Sulphuric  acid  being  dibasic,  there  exist  two  sulphates 
of  the  univalent  metals:  HKSO4  and  K2S04,  and  but  one  sulphate 
of  each  bivalent  metal :  CaS04.  The  sulphates  of  Ba,  Ca,  Sr,  and  Pb 
are  insoluble,  or  very  sparingly  soluble,  in  H20.  Other  sulphates  are 
soluble  in  H20,  but  all  are  insoluble  in  alcohol. 

Analytical  Characters. — Because  of  the  dibasic  character  of  sul- 
phuric acid  its  solutions  and  those  of  its  salts  may  contain  two  kinds 
of  anion:  S04"  in  dilute  solutions  of  the  acid  and  in  solutions  of 
neutral  sulphates,  and  S04H'  in  concentrated  solutions  of  the  acid 
and  in  solutions  of  acid  sulphates.  In  the  following  analytical  re- 
actions it  is  immaterial  which  anion  is  present  if  the  reaction  bo 
only  slightly  acid,  because  then,  as  SO/'  is  removed  by  combination 
with  the  cations  Ba",  Pb",  or  Ca",  the  anion  S04H'  is  decom- 
posed to  SO/+H';  but  when  the  solution  is  strongly  acid  a  small 
proportion  of  S04H'  may  remain  unprecipitated. 

(1)  Barium  chloride  (or  nitrate)  ;  a  white  ppt.,  insol.  in  dil. 
acids.  The  ppt.,  dried  and  heated  with  charcoal,  forms  BaS,  which, 
with  HC1,  gives  off  H2S.  (2)  Plumbic  acetate  forms  a  white  ppt., 
insol.  in  dil.  acids.  (3)  Calcium  chloride  forms  a  white  ppt.,  either 
immediately  or  upon  dilution  with  two  volumes  of  alcohol:  insol. 
in  dil.  HC1  or  HN03. 

Toxicology. — Sulphuric  acid  is  an  active  corrosive,  and  may  be,  if  taken 
in  sufficient  quantity  in  a  highly  diluted  state,  a  true  poison.  The  concentrated 
acid  causes  death,  either  within  a  few  hours,  by  corrosion  and  perforation  of 
the  walls  of  the  stomach  and  esophagus,  or,  after  many  weeks,  by  starvation, 
due  to  destruction  of  the  gastric  mucous  membrane  and  closure  of  the  pyloric 
orifice  of  the  stomach. 

The  treatment  is  the  same  as  that  for  corrosion  by  HC1    'see  page  79). 

Persulphuric  Acid. — H2S208 — 194 — is  formed  by  the  electrolysis 
of  concentrated  sulphuric  acid: 

2H2S04=H2S208+H:!; 

or  by  the  action  of  hydrogen  dioxide  on  sulphuric  acid : 
2H2S04+H202=H2S208+2H20 

It  crystallizes  at  0°  in  long,  transparent  needles.  The  correspond- 
ing anhydride,  S207,  is  formed  by  the  action  of  high  tension  electric 
currents  in  a  mixture  of  dry  S02  and  0. 

Thiosulphuric  Acid. — Hyposulphurous  acid — H2S203 — 314 — may 
be  considered  as  sulphuric  acid,  H2S04,  in  which  one  atom  of  oxygen 
has  been  replaced  by  one  of  sulphur.  The  acid  itself  has  not  been 
isolated,  being  decomposed,  on  liberation  from  the  thiosulphates,  into 
sulphur,  water,  and  sulphur  dioxide: 

H2S203=S+S02+H20 


NITROGEN   GROUP  93 

Pyrosulphuric  Acid. — Fuming  sulphuric  acid — Nordhausen  oil  of 
vitriol — H2S207 — Molecular  weigJit=H8—Sp.  #r.=1.9. 

Preparation. — By  distilling  ferrous  sulphate;  and  purification  of 
the  product  by  repeated  crystallizations  and  fusions,  until  a  sub- 
stance fusing  at  35  °  is  obtained. 

Properties. — The  commercial  Nordhausen  acid,  which  is  a  mix- 
ture of  H2S207  with  excess  of  S03,  or  of  H2S04,  is  a  brown,  oily 
liquid,  which  boils  below  100  °,  giving  off  S03 ;  and  is  solid  or  liquid 
according  to  the  temperature.  It  is  used  chiefly  as  a  solvent  for 
indigo,  and  in  the  aniline  industry. 


SELENIUM  AND  TELLURIUM. 
Se— 79  (International=79.2)     Te— 127  (International=127.5) 

These  are  rare  elements  which  form  compounds  similar  to  those 
of  sulphur.  Selenium  is  known  in  various  allotropic  modifications, 
and  is  used  in  some  forms  of  electrical  apparatus. 

III.    NITROGEN  GROUP. 

NITROGEN— PHOSPHORUS— ARSENIG-ANTIMONY. 

The  elements  of  this  group  are  trivalent  or  quinquivalent,  occa- 
sionally univalent.  With  hydrogen  they  form  non-acid  compounds, 
composed  of  one  volume  of  the  element  in  the  gaseous  state  with 
three  volumes  of  hydrogen,  the  union  being  attended  with  a  conden- 
sation of  volume  of  one-half. 

Bismuth,  frequently  classed  in  this  group,  is  excluded,  owing  to 
the  existence  of  the  nitrate  Bi(N03)3.  The  relations  existing  between 
the  compounds  of  the  elements  of  this  group  are  shown  in  the  follow- 
ing table: 

NH3,  N2O,            NO,             NA,  N02,            N205, 

PH3,  PA,                               PA,            H3P02, 

AsH3,  AsA,                              AsA, 

SbH3,  SbA,  SbA,          SbA, 

Hyd-  Mon-  Di-  Tri-  Tetr-  Pent-  Hypo-ous 

ride.  oxide.  oxide.  oxide.  oxide.  oxide.  acid. 

HN02,  HN03, 

H3P03,  H4P2O5,  H3P04,  H4P207,  HPO3, 

H3As03,  H4As205,  HAs02,  H3As04,  H4As207,  HAs03, 

HSb02,  H3Sb04,  H4Sb207,  HSbO3, 

-ous  Pyro-ous  Meta-ous  -Ic  Pyro-ic  Meta-ic 

acid.  acid.  acid.  acid.  acid.  acid. 


94  TEXT-BOOK   OF   CHEMISTRY 

NITROGEN. 

« 

Azote — Symbol=N — Atomic  weight=14:  (International=14.Ql) — 
Molecular  weight— 2S—Sp.  #r.=0.9701. 

Occurrence. — Free  in  atmospheric  air  and  in  volcanic  gases.  In 
combination  in  the  nitrates,  in  ammoniacal  compounds  and  in  a  great 
number  of  animal  and  vegetable  substances. 

Preparation. —  (1)  By  removal  of  0  from  atmospheric  air;  by 
burning  P  in  air,  or  by  passing  air  slowly  over  red-hot  copper.  It  is 
contaminated  with  C02,  H20,  etc. 

(2)  By  passing  Cl  through  excess  of  ammonium  hydroxide  solu- 
tion.    If  ammonia  is  not  maintained  in  excess,  the  Cl  reacts  with 
the  ammonium  chloride  formed,   to  produce  the  terribly  explosive 
nitrogen  chloride. 

(3)  By  heating  ammonium  nitrite  (NH4)N02: 

NH4NO2=2H20+N2 

(4)  By  heating  a  mixture  of  ammonium  chloride  and  potassium 
nitrite : 

KN02+NH4C1=KC1+NH4N02 

The  ammonium  nitrite  then  splits  up  as  in  (3). 

Properties. — A  colorless,  odorless,  tasteless,  non-combustible  gas; 
not  a  supporter  of  combustion;  very  sparingly  soluble  in  water. 

It  is  very  slow  to  enter  into  combination,  and  most  of  its  com- 
pounds are  very  prone  to  decomposition,  which  may  occur  explo- 
sively or  slowly.  Nitrogen  combines  directly  with  0  under  the 
influence  of  electric  discharges;  and  with  H  under  like  conditions, 
and,  directly,  during  the  decomposition  of  nitrogenized  organic  sub- 
stances. It  combines  directly  with  magnesium,  boron,  vanadium, 
and  titanium. 

Nitrogen  is  not  poisonous,  but  is  incapable  of  supporting  respi- 
ration. 

Atmospheric  Air. — Composition. — Air  is  not  a  chemical  compound,  but  a 
mechanical  mixture  of  O  and  N,  with  smaller  quantities  of  other  gases  (see 
page  72).  Leaving  out  of  consideration  vapor  of  water  and  small  quantities  of 
other  gases,  except  0.03  of  carbon  dioxide,  air  consists  of  20.95  O  and  79.02  N 
(including  argon),  by  volume;  or  about  23  O  and  77  N,  by  weight;  proportions 
which  vary  but  very  slightly  at  different  times  and  places. 

That  air  is  not  a  compound  is  shown  by  the  fact  that  the  proportion  of 
its  constituents  does  not  represent  a  relation  between  their  atomic  weights,  or 
between  any  multiples  thereof;  as  well  as  by  the  solubility  of  air  in  water. 
Were  it  a  compound  it  would  have  a  definite  degree  of  solubility  of  its  own, 
and  the  dissolved  gas  would  have  the  same  composition  as  when  free.  But 
each  of  its  constituents  dissolves  in  H2O  according  to  its  own  solubility,  and 
air  dissolved  in  H2  O  at  14.1°  consists  of  N  and  O,  not  in  the  proportion  given 
above,  but  in  the  proportion  of  66.76  to  33.24. 

Besides  these  two  main  constituents,  air  contains  about  4-5  thousandths  of 


NITROGEN  95 

its  bulk  of  other  substances;  vapor  of  water,  carbon  dioxide,  ammoniacal  com- 
pounds, hydrocarbons,  ozone,  oxides  of  nitrogen,  and  solid  particles  held  in 
suspension. 

Vapor  of  Water. — Atmospheric  moisture  is  either  visible,  as  in  fogs  and 
clouds,  when  it  is  in  the  form  of  a  finely  divided  liquid;  or  invisible,  as  vapor 
of  water.  The  amount  of  H2O  which  a  given  volume  of  air  can  hold,  without 
precipitation,  varies  according  to  the  temperature  and  pressure.  It  happens 
rarely  that  air  is  as  highly  charged  with  moisture  as  it  is  capable  of  being 
for  the  existing  temperature.  The  fraction  of  saturation,  or  hygrometric 
state,  or  relative  humidity  of  the  atmosphere  is  the  percentage  of  that  quantity 
of  vapor  of  water  which  the  air  could  hold  at  the  existing  temperature  and 
pressure  which  it  actually  does  hold.  Thus  air  with  a  humidity  of  100  is 
saturated,  and  a  diminution  of  temperature  or  of  pressure  would  cause  precipi- 
tation; but  an  increase  of  temperature  or  of  pressure  would  cause  a  diminution 
of  humidity.  Ordinarily  air  contains  from  66  to  70  per  cent,  of  its  possible 
amount  of  moisture.  If  the  quantity  is  less  than  this,  the  air  is  dry,  and 
causes  a  parched  sensation,  and  the  sense  of  "stuffiness"  so  common  in  furnace- 
heated  houses.  If  it  be  greater,  evaporation  from  the  skin  is  impeded,  and  the 
air  is  oppressive  if  warm. 

The  actual  amount  of  moisture  in  air  is  determined  by  passing  a  known 
volume  through  tubes  filled  with  calcium  chloride,  whose  increase  in  weight 
represents  the  amount  of  H2O  in  the  volume  of  air  used.  The  humidity  is  de- 
termined by  instruments  called  hygrometers,  hygroscopes  or  psychrometers. 

Carbon  Dioxide. — The  quantity  of  carbon  dioxide  in  free  air  varies  from 
3  to  6  parts  in  10,000  by  volume.  (See  Carbon  dioxide.) 

For  the  newer  gases  in  the  air,  see  page  72. 

Ammoniacal  Compounds. — Carbonate,  nitrate,  and  nitrite  of  ammonium 
occur  in  small  quantity  (0.1  to  6.0  parts  per  million  of  NH3)  in  air,  as  products 
of  the  decomposition  of  nitrogenized  organic  substances.  They  are  absorbed  and 
assimilated  by  plants. 

Nitric  and  Nitrous  acids,  usually  in  combination  with  ammonium,  are 
produced  either  by  the  oxidation  of  combustible  substances  containing  N,  or  by 
direct  union  of  N  and  H20  during  discharges  of  atmospheric  electricity.  Rain- 
water, falling  during  thunder-showers,  has  been  found  to  contain  as  much  as 
3.71  per  million  of  HNO3. 

Sulphuric  and  Sulphurous  acids  occur,  in  combination  with  NH4,  in  the 
air  over  cities,  and  manufacturing  districts,  where  they  are  produced  by  the 
oxidation  of  S,  existing  in  coal  and  coal-gas. 

Solid  particles  of  the  most  diverse  nature  are  always  present  in  air  and 
become  visible  in  a  beam  of  sunlight.  Sodium  chloride  is  almost  always  present, 
always  in  the  neighborhood  of  salt  water.  Air  contains  myriads  of  germc  of 
vegetable  organisms,  mould,  etc.,  which  are  propagated  by  the  transportation  of 
these  germs  by  air-currents. 

Compounds  of  Nitrogen  and  Hydrogen. — Three  are  known: 
Ammonia,  NH3 ;  Hydrazine,  N2H4 ;  and  Hydrazoic  acid,  N3H ;  as 

well  as  salts  corresponding  to  two  hydroxides. 

Ammonia. — Hydrogen  nitride — Volatile  alkali — NH3 — Molecular 
weight— Yl— Sp.  #r.=0.589  A. 

Preparation. — (1)  By  union  of  nascent  H  with  N. 
(2)  By   decomposition   of   organic   matter   containing  N,    either 
spontaneously  or  by  destructive  distillation. 


96  TEXT-BOOK   OF   CHEMISTRY 

(3)  By  heating  solution  of  ammonium  hydroxide: 

NH4OH=NH3-f-H20. 

(4)  By  heating  a  mixture  of   ammonium   chloride   and  slaked 
lime: 

2NH4Cl+Ca(OH)2=CaCl2+2H20+2NH3 

Properties. — Physical. — A  colorless  gas,  having  a  pungent  odor, 
and  an  acrid  taste.  It  is  very  soluble  in  H20,  1  volume  of  which  at 
0°  dissolves  1050  vols.  NH3,  and  at  15°  727  vols.  NH3.  Alcohol 
and  ether  also  dissolve  it  readily.  Liquid  ammonia  is  a  colorless, 
mobile  fluid,  used  in  ice  machines  for  producing  artificial  cold,  the 
liquid  absorbing  a  great  amount  of  heat  in  volatilizing. 

Chemical. — At  a  red  heat  ammonia  is  decomposed  into  a  mixture 
of  N  and  H,  occupying  double  the  volume  of  the  original  gas.  It  is 
similarly  decomposed  by  the  prolonged  passage  through  it  of  dis- 
charges of  electricity.  It  is  not  readily  combustible,  yet  it  burns  in  an 
atmosphere  of  0  with  a  yellowish  flame.  Mixtures  of  NH3  with  0, 
nitrogen  monoxide,  or  nitrogen  dioxide,  explode  on  contact  with  flame. 

The  solution  of  ammonia  in  H20  constitutes  a  strongly  alkaline 
liquid,  known  in  the  U.  S.  P.  as  aqua  ammonias  (ammonia  water), 
which  contains  not  less  than  9.5  per  cent,  nor  more  than  10.5  per  cent. 
NH3,  and  is  possessed  of  strongly  basic  properties.  It  is  neutralized 
by  acids  with  the  formation  of  crystalline  salts,  which  are  also 
formed,  without  liberation  of  hydrogen,  by  direct  union  of  gaseous 
NH3  with  acid  vapors.  The  ammoniacal  salts  and  the  alkaline  base 
in  aqua  ammoniae  are  compounds  of  a  radical,  ammonium,  NH4, 
which  forms  compounds  corresponding  to  those  of  potassium  or 
sodium.  The  compound  formed  by  the  union  of  ammonia  and 
water  is  ammonium  hydroxide,  NH4OH: 

NH3+H20=NH4OH ; 

and  that  formed  by  the  union  of  hydrochloric  acid  and  ammonia  is 
ammonium  chloride,  NH4C1: 

NH3+HC1=NH4C1. 

A  very  delicate  test  for  ammonia  is  Nessler's  reagent.  This  is 
made  by  dissolving  35  gm.  of  potassium  iodide  and  13  gm.  of  mercuric 
chloride  in  800  cc.  H20.  A  cold,  saturated  solution  of  mercuric 
chloride  is  then  added,  drop  by  drop,  until  the  red  precipitate  formed 
no  longer  redisselves  on  agitation ;  160  gm.  of  potassium  hydroxide 
are  then  dissolved  in  the  liquid,  which  is  finally  made  up  to  1000  cc. 
It  gives  a  yellow  color  with  a  mere  trace  of  NH3,  and  a  red-brown 
precipitate  with  a  larger  amount. 

Hydrazine — Diamide — H2N.NH2 — is  known  in  the  form  of  its  hydroxide, 
corresponding  to  ammonium  hydroxide,  in  the  form  of  its  salts  and  in  numerous 
organic  derivatives.  The  sulphate  is  produced  by  the  action  of  H2SO4  upon 


NITROGEN  97 

triazoacetic  acid,  and  the  hydroxide  by  decomposition  of  the  sulphate  by  caustic 
soda.  The  hydroxide  is  an  oily  liquid,  intensely  corrosive,  capable  of  attacking 
glass,  ft  combines  with  acids  to  form  well-defined  salts,  and  precipitates  many 
metals  from  solutions  of  their  salts.  It  is  an  active  poison. 

Hydrazoic  Acid— Azoimide — N3H — is  a  substance  obtained  from  benzoyl- 
azoimide,  which,  although  containing  the  same  elements  as  ammonia,  is  dis- 
tinctly acid  in  character.  It  is  a  colorless  liquid,  boiling  at  37°,  having  a 
very  pungent  and  unpleasant  odor.  It  is  extremely  unstable  and  explodes  with 
great  violence.  It  reacts  with  metals,  oxides,  and  hydroxides,  as  does  hydro- 
chloric acid,  to  form  nitrides,  which,  like  the  free  acid,  are  very  explosive.  It 
is  a  very  active  poison. 

Hydroxylamine — NH2OH — 33. — The  amines  and  amides  (q.  v.)  are  com- 
pounds derived  from  ammonia  by  the  substitution  of  radicals  for  a  part  or  all 
of  its  hydrogen.  The  substance,  which  is  intermediate  in  composition  between 
ammonia  and  ammonium  hydroxide,  may  be  considered  as  ammonia,  one  of 
whose  hydrogen  atoms  has  been  replaced  by  the  radical  hydroxyl,  OH.  It  is 
obtained  in  aqueous  solution  by  the  union  of  nascent  hydrogen  with  nitrogen 
dioxide:  NO-j-H3rrrNH2HO ;  or  by  the  action  of  nascent  hydrogen  upon  nitric 
acid:  HNO3-f-3H2=2H20-f-NH2HO.  Hydroxylamine  has  been  obtained  in  color- 
less, hygroscopic  crystals  at  33°,  by  systematic  rectification  of  the  methyl 
alcohol  solution  under  diminished  pressure,  and  by  distillation  of  the  Zn  double 
salt,  ZnCl2,  2NH2HO  with  aniline.  Its  aqueous  solution,  which  probably  con- 
tains the  corresponding  hydroxide,  NH3,  OH,  is  strongly  alkaline  and  behaves 
with  regard  to  acids  as  does  ammonium  hydroxide  solution,  forming  salts  cor- 
responding to  those  of  ammonium.  Thus  hydroxyl-ammonium  chloride,  NH4OC1, 
crystallizes  in  prisms  or  tables,  fusible  at  100°,  and  decomposed  into  HC1, 
H2O  and  NH4C1  at  a  slightly  higher  temperature.  It  is  a  very  powerful  reducing 
agent. 

Compounds  of  Nitrogen  with  the  Halogens. — Nitrogen  Chloride 
— NC13 — 120.5 — is  formed  by  the  action  of  excess  of  Cl  upon  NH3  or 
an  ammoniacal  compound.  It  is  an  oily,  light-yellow  liquid;  sp.  gr. 
1.653;  has  been  distilled  at  71°.  When  heated  to  96°,  when  sub- 
jected to  concussion,  or  when  brought  in  contact  with  phosphorus, 
alkalies  or  greasy  matters,  it  is  decomposed,  with  a  violent  explosion, 
into  one  volume  N  and  three  volumes  Cl. 

Nitrogen  Bromide. — NBr3 — 254 — has  been  obtained  as  a  reddish- 
brown,  syrupy  liquid,  very  volatile,  and  resembling  the  chloride  in  its 
properties,  by  the  action  of  potassium  bromide  upon  nitrogen  chloride. 

Nitrogen  Iodide. — NI3 — 395 — When  iodine  is  brought  in  contact 
with  ammonium  hydroxide  solution,  a  dark  brown  or  black  powder, 
highly  explosive  when  dried,  is  formed.  This  substance  varies  in 
composition  according  to  the  conditions  under  which  the  action 
occurs;  sometimes  the  iodide  alone  is  formed;  under  other  circum- 
stances it  is  mixed  with  compounds  containing  N,  I,-  and  H. 

Oxides  of  Nitrogen. — Five  are  known,  forming  a  regular  series: 
N20,  NO,  N203,  N2O4,  N205.  Of  these  two,  the  trioxide,  N203,  and 
pentcxide,  N205,  are  anhydrides. 

Nitrogen  Monoxide. — Nitrogenii  monoxidum  (U.  S.  P.) — Nitrous 
oxide  —  Laughing  gas — N20  —  Molecular  weight  =  44  —  Sp.  gr.  = 
1.527  A. 


98  TEXT-BOOK   OF   CHEMISTRY 

Preparation. — By  heating  ammonium  nitrate : 
(NH4)N08=N20+2H20 

To  obtain  a  pure  product  there  should  be  no  ammonium  chloride 
present  (as  an  impurity  of  the  nitrate),  and  the  heat  should  be 
applied  gradually  and  not  allowed  to  exceed  250°,  and  the  gas 
formed  should  be  passed  through  wash-bottles  containing  sodium 
hydroxide  and  ferrous  sulphate. 

Properties. — Physical. — A  colorless,  odorless  gas,  having  a 
sweetish  taste  soluble  in  H20;  more  so  in  alcohol.  Under  a  pres- 
sure of  30  atmospheres,  at  0°,  it  forms  a  colorless,  mobile  liquid 
which,  when  dissolved  in  carbon  disulphide  and  evaporated  in  vacuo, 
produces  a  cold  of  — 140°. 

Chemical. — It  is  decomposed  by  a  red  heat  and  by  the  continuous 
passage  of  electric  sparks.  It  is  not  combustible,  but  is,  after 
oxygen,  the  best  supporter  of  combustion  known. 

Physiological. — Although,  owing  to  the  readiness  with  which 
N20  is  decomposed  into  its  constituent  elements,  and  the  nature  and 
relative  proportions  of  these  elements,  it  is  capable  of  maintaining 
respiration  longer  than  any  gas  except  oxygen  or  air,  an  animal  will 
live  for  a  short  time  only  in  an  atmosphere  of  pure  nitrous  oxide. 
When  inhaled,  diluted  with  air,  it  produces  the  effects  first  observed 
by  Davy  in  1799 :  first  an  exhilaration  of  spirits,  frequently  accom- 
panied by  laughter,  and  a  tendency  to  muscular  activity,  the  patient 
sometimes  becoming  aggressive ;  afterward  there  is  complete  anesthesia 
and  loss  of  consciousness.  It  is  much  used,  by  surgeons  and  dentists, 
as  an  anesthetic  in  operations  of  short  duration. 

Nitrogen  Dioxide. — Nitric  oxide — NO — Molecular  weight=2Q — 
Sp.  #r.=1.039  A. 

Preparation. — By  the  action  of  copper  on  moderately  diluted 
nitric  acid  in  the  cold: 

3Cu+8HN03=3Cu(N03)2+4H20+2NO ; 

the  gas  being  collected  after  displacement  of  air  from  the  apparatus. 

Properties. — A  colorless  gas,  whose  odor  and  taste  are  unknown; 
very  sparingly  soluble  in  H20 ;  more  soluble  in  alcohol.  The  sp.  gr.  of 
the  gas  has  been  determined  at  — 100°  and  has  been  found  to  be  same 
as  at  ordinary  temperature.  This  fixes  the  molecular  weight  at  30 
and  gives  the  formula  NO,  which  is  difficult  to  reconcile  with  the 
theory  of  valence.  Were  the  formula  doubled  the  constitution  of 
this  gas  could  be  thus  expressed:  0=N— N=0.  (See  Nitrogen 
tetroxide.) 

It  combines  with  0,  when  mixed  with  that  gas  or  with  air,  to 
form  the  reddish  brown  nitrogen  tetroxide.  It  is  absorbed  by  solu- 
tion of  ferrous  sulphate,  to  which  it  communicates  a  dark  brown  or 


NITROGEN  99 

black  color.  It  is  neither  combustible  nor  a  good  supporter  of  com- 
bustion, .although  ignited  C  and  P  continue  to  burn  in  it,  and  the 
alkaline  metals,  when  heated  in  it,  combine  with  its  0  with  incan- 
descence. 

Nitrogen  Trioxide. — Nitrous  anhydride. — N203 — 76 — Is  prepared 
by  the  direct  union  of  nitrogen  dioxide  and  oxygen  at  low  tempera- 
tures, or  by  decomposing  liquefied  nitrogen  tetroxide  with  a  small 
quantity  of  H20  at  a  low  temperature : 

4N02+H20=2HN03+N203 

It  is  a  dark  indigo-blue  liquid,  which,  boiling  at  about  0°,  is 
partly  decomposed.  It  solidifies  at  — 82°. 

Nitrogen  Tetroxide.  —  Nitrogen  peroxide.  —  N204  —  Molecular 
weight=92. 

Preparation. —  (1)  By  mixing  one  volume  0  with  two  volumes 
NO ;  both  dry  and  ice-cold. 

(2)  By  heating  perfectly  dry  lead  nitrate,  0  being  also  produced: 

2Pb(N03)2=2PbO+4N02+02. 

(3)  By  dropping  strong  nitric   acid  upon   a  red-hot  platinum 
surface. 

Properties. — When  pure  and  dry,  it  is  an  orange-yellow  liquid  at 
the  ordinary  temperature;  the  color  being  darker  the  higher  the 
temperature;  the  gas  is  red-brown,  but  becomes  colorless  at  about 
500°.  The  red  fumes,  which  are  produced  when  nitric  acid  is  de- 
composed by  starch  or  by  a  metal,  consist  of  N204,  mixed  with  N203. 
The  sp.  gr.  of  the  gas  varies  with  the  temperature  and  pressure. 
Values  varying  from  29.23  to  39.9  have  been  obtained  (H=l).  The 
molecular  formula,  N02,  calls  for  sp.  gr.  23;  N204  for  46.  These 
variations  are  due  to  the  fact  that  the  gas  is  dissociated  at  com- 
paratively low  temperatures.  The  formula  N204  has  been  fixed  as 
the  correct  one  by  the  method  of  Raoult.  It  dissolves  in  nitric  acid, 
forming  a  dark  yellow  liquid,  which  is  blue  or  green  if  N203  be 
also  present.  With  S02  it  combines  to  form  a  solid,  crystalline  com- 
pound, which  is  sometimes  produced  in  the  manufacture  of  H2S04. 
This  substance,  which  forms  the  lead  chamber  crystals,  is  a  sub- 
stituted sulphurous  acid,  nitrosulphonic  acid,  N02S02OH  (see 
sulphonic  acids).  A  small  quantity  of  H20  decomposes  N204  into 
HN03  and  N203,  which  latter  colors  it  green  or  blue.  A  larger 
quantity  of  H20  decomposes  it  into  HN03  and  NO.  By  bases  it  is 
transformed  into  a  mixture  of  nitrite  and  nitrate: 

2N02+2KOH=KN02+KNOS+H20 

It  is  an  energetic  oxidant,  for  which  it  is  largely  used.     With 


100  TEXT-BOOK   OF   CHEMISTRY 

certain  organic  substances  it  does  not  behave  as  an  oxidant,  but 
becomes  substituted  as  an  univalent  radical;  thus  with  benzene  it 
forms  nitro-benzene :  C0H5(N(X). 

Toxicology. — The  brown  fumes  given  off  during  many  processes,  in  which 
nitric  acid  is  decomposed,  are  dangerous  to  life.  When  in  industrial  processes 
the  volume  of  gas  formed  becomes  such  as  to  be  a  nuisance  when  discharged 
into  the  air,  it  should  be  utilized  in  the  manufacture  of  H2S04,  or  absorbed  by 
H20  or  an  alkaline  solution. 

An  atmosphere  contaminated  wi'h  brown  fumes  is  more  dangerous  than 
one  containing  Cl,  as  the  presence  of  the  latter  is  more  immediately  annoying. 
At  first  there  is  only  coughing,  and  it  is  only  two  to  four  hours  later  that  a 
difficulty  in  breathing  is  felt,  death  occurring  in  ten  to  fifteen  hours. 

Even  air  containing  small  quantities  of  brown  fumes,  if  breathed  for  a 
long  time,  produces  chronic  disease  of  the  respiratory  organs.  To  prevent  such 
accidents,  thorough  ventilation  in  locations  where  brown  fumes  are  liable  to 
be  formed  is  imperative,  In  cases  of  spilling  nitric  acid,  safety  is  to  be  sought 
in  retreat  from  the  apartment  until  the  fumes  have  been  replaced  by  pure  air 
from  without. 

Nitrogen  Pentoxide. — Nitric  anhydride — N20S — Molecular  weight 
=108. 

Preparation. — (1)  By  decomposing  dry  silver  nitrate  with  dry  Cl 
in  an  apparatus  entirely  of  glass: 

4AgN03+2Cl2=4AgCl+02+2N2Oc. 

(2)  By  removing  water  from  fuming  nitric  acid  with  phosphorus 
pentoxide : 

6HN03+PA=2H3P04+3N205. 

Properties. — Prismatic  crystals  at  temperatures  above  30°.  It  is 
very  unstable,  being  decomposed  by  a  heat  of  50°;  on  contact  with 
H20,  with  which  it  forms  nitric  acid;  and  even  spontaneously.  Most 
substances  which  combine  readily  with  0  remove  that  element 
from  N205. 

Nitrogen  Acids. — Three  are  known,  either  free  or  in  combination, 
corresponding  to  the  three  oxides  containing  uneven  numbers  of  0 
atoms : 

N20 -|-H2O=2HNO — Hyponitrous   acid. 
N203+H20=2HNO,— Nitrous  acid. 
N20S+H20=2HNO,— Nitric  acid. 

Hyponitrous  Acid — HNO — 31 — Known  only  in  combination. 
Sodium  hyponitrite  is  formed  by  the  action  of  sodium  upon  sodium 
nitrate,  or  nitrite : 

NaN03+4Na+2H20=NaNO+4NaOH 

Silver  hyponitrite   is   formed  by   reduction   of   sodium   nitrate   by 
nascent  H  and  decomposition  with  silver  nitrate. 


NITROGEN  101 

Nitrous  Acid — Metanitrons  acid — HN(X — 47 — has  not  been  iso- 
lated, although  its  salts,  the  nitrites,  are  well-defined  compounds: 
M'N026rM"(N02)2. 

The  nitrites  occur  in  nature,  in  small  quantity,  in  natural  waters; 
where  they  result  from  the  decomposition  of  nitrogenous  organic  sub- 
stances; also  in  saliva.  They  are  produced  by  heating  the  corre- 
sponding nitrate,  either  alone  or  in  the  presence  of  a  readily  oxidizable 
metal,  such  as  lead.  Solutions  of  the  nitrites  are  readily  decomposed 
by  the  mineral  acids,  with  evolution  of  brown  fumes.  They  take  up 
oxygen  readily  and  are  hence  used  as  reducing  agents.  Solutions  of 
potassium  permanganate  are  instantly  decolorized  by  nitrites.  A 
mixture  of  thin  starch  paste  and  zinc  iodide  solution  is  colored  blue 
by  nitrites,  which  decompose  the  iodide,  liberating  the  iodine.  A  solu- 
tion of  metaphenylendiamine,  in  the  presence  of  free  acid,  is  colored 
brown  by  very  minute  traces  of  a  nitrite,  the  color  being  due  to  the 
formation  of  triamido-azobenzene  (Bismark  brown). 

Nitric  Acid.  Aquafortis — Acidum  nitricum — U.  S.  P. — 
HN03— 63. 

Preparation. —  (1)  By  the  direct  union  of  its  constituent  elements 
under  the  influence  of  electric  discharges. 

(2)  By  the  decomposition  of  an  alkaline  nitrate  by  strong  H2S04. 
With  moderate  heat  a  portion  of  the  acid  is  liberated: 

2NaN03+H2S04=NaHS04+NaN03+HN03, 
and  at  a  higher  temperature  the  remainder  is  given  off: 
NaN03+NaHS04==Na2S04+HN03 

This  is  the  reaction  used  in  the  manufacture  of  HN03. 

Varieties. — Commercial — a  yellowish  liquid,  impure,  and  of  two 
degrees  of  concentration:  single  aquafortis;  sp.  gr.  about  1.25=39% 
HN03;  and  double  aquafortis;  sp.  gr.  about  1.4=64%  HN03. 
Fuming — a  reddish  yellow  liquid,  more  or  less  free  from  impurities; 
charged  with  oxides  of  nitrogen.  Sp.  gr.  about  1.5.  Used  as  an 
oxidizing  agent.  C.  P. — a  colorless  liquid,  sp.  gr.  1.522,  which 
should  respond  favorably  to  the  tests  given  below.  Acidum  nitri- 
cum, U.  S.  P.— a  colorless  acid,  of  sp.  gr.  1.403  at  25°=67  to  69 
per  cent.  HN03. 

Properties. — Physical. — The  pure  acid  is  a  colorless  liquid:  sp. 
gr.  1.522;  boils  at  86°;  solidifies  at  — 40°;  gives  off  white  fumes  in 
damp  air;  and  has  a  strong  acid  taste  and  reaction. 

Chemical. — When  exposed  to  air  and  light,  or  when  strongly 
heated,  HN03  is  decomposed  into  N204 ;  H20  and  0.  Nitric  acid  is 
a  valuable  oxidant;  it  converts  I,  P,  S,  C,  B,  and  Si  or  their  lower 
oxides  into  their  highest  oxides ;  it  oxidizes  and  destroys  most  organic 
substances,  although  with  some  it  forms  products  of  substitution. 


102  TEXT-BOOK  OF  CHEMISTRY 

Most  of  the  metals  dissolve  in  HN03  as  nitrates,  a  portion  of  the 
acid  being  at  the  same  time  decomposed  into  NO  and  H20 : 

4HN03+3Ag=3AgN03+NO+2H20. 

The  chemical  activity  of  HN03  is  much  reduced,  or  even  almost 
arrested,  when  the  intervention  of  nitrous  acid  is  prevented  by  the 
presence  of  carbamide.  The  so-called  noble  metals,  gold  and  plati- 
num, are  not  dissolved  by  either  HN03  or  HC1,  but  dissolve  as 
chlorides  in  a  mixture  of  the  two  acids,  called  aqua  regia.  In  this 
mixture  the  two  acids  mutually  decompose  each  other  according  to 
the  equations : 

HN03+3HC1=2H20+NOC1+C12  and 
2HN03+6HC1— 4H20+2NOC12+C12 

with  formation  of  nitrosyl  chloride,  NOC1,  and  bichloride,  NOC12,  and 
nascent  Cl;  the  last  named  combining  with  the  metal.  The  acidum 
nitrohydrochloricum  of  the  U.  S.  P.  is  a  strong  aqueous  solution  con- 
taining hydrochloric  acid,  nitric  acid,  nitrosyl  chloride,  and  chlorine. 
There  is  also  an  acidum  nitrohydrochloricum  dilutum  (U.  S.  P.), 
which  is  a  diluted  aqueous  solution  containing  the  same  constituents 
as  the  stronger  acid.  Iron  dissolves  easily  in  dilute  HN03,  but  if 
dipped  into  the  concentrated  acid,  it  is  rendered  passive,  and  does 
not  dissolve  when  subsequently  brought  in  contact  with  the  dilute 
acid.  This  passive  condition  is  destroyed  by  a  temperature  of  40° 
(104°  F.)  or  by  contact  with  Pt,  Ag  or  Cu.  When  HN03  is  decom- 
posed by  zinc  or  iron,  or  in  the  porous  cup  of  a  Grove  battery,  N.,03 
and  N204  are  formed,  and  dissolve  in  the  acid,  which  is  colored  dark 
yellow,  blue  or  green.  An  acid  so  charged  is  known  as  nitroso-nitric 
acid.  Nitric  acid  is  monobasic. 

Impurities. — Oxides  of  nitrogen  color  the  acid  yellow:  H2S04  gives  a  white 
ppt.  with  BaCl2;  Cl,  a  white  ppt.  with  AgNO3;  and  Fe  a  red  color  with  ammo- 
nium thiocyanate.  Dilute  the  acid  with  two  volumes  of  water  before  testing. 
Salts  leave  a  solid  residue  when  the  acid  is  evaporated  in  platinum. 

Nitrates. — The  nitrates  of  K  and  Na  occur  in  nature.  Nitrates 
are  formed  by  the  action  of  HN03  on  the  metals,  or  on  their  oxides 
or  carbonates.  They  have  the  composition  M'N03,  M"(N03)2  or 
M'"(N03)8,  except  certain  basic  salts,  such  as  the  sesquibasic  lead- 
nitrate,  Pb  (N03)2,  2PbO.  With  the  exception  of  a  few  basic  salts, 
the  nitrates  are  all  soluble  in  water.  When  heated,  they  fuse  and  act 
as  powerful  oxidants.  They  are  decomposed  by  H2S04  with  libera- 
tion of  HNO.,. 

Analytical  Characters. — As  the  nitrates  are  all  soluble,  there  is 
no  precipitation  reaction  for  the  anion  N03',  and  recourse  is  had  to 
color  reactions:  (1)  Add  an  equal  volume  of  concentrated  IL,S04, 
cool,  and  float  on  the  surface  of  the  mixture  a  solution  of  FeS04. 


PHOSPHORUS  103 

The  lower  layer  becomes  gradually  colored  brown,  black,  or  purple, 
beginning  at  the  top. 

(2)  Boil   in   a   test-tube   a   small   quantity   of   HC1,   containing 
enough  sulphindigotic  acid  to  communicate  a  blue  color,  add  the  sus- 
pected solution  and  boil  again;  the  color  is  discharged. 

(3)  If  acid,  neutralize  with  KOH,  evaporate  to  dryness,  add  to 
the  residue  a  few  drops  of  H2S04  and  a  crystal  of  brucine  (or  some 
sulphanilic  acid)  ;  a  red  color  is  produced. 

(4)  Add  H,S04  and  Cu  to  the  suspected  liquid  and  boil,  brown 
fumes  appear  (best  visible  by  looking  into  the  mouth  of  the  test  tube). 

(5)  A  solution  of  diphenylamine  in  concentrated  H2S04  (.01  grm. 
in  100  cc.)  is  colored  blue  by  nitric  acid.    A  similar  color  is  produced 
by  other  oxidizing  agents. 

(6)  To  0.5  cc.  nitrate  solution  add  one  drop  aqueous  solution  of 
resorcinol  (10%),  and  1  drop  HC1  (15%),  and  float  on  the  surface  of 
2  cc.  concentrated  H2S04;  a  purple-red  band. 

Toxicology. — Although  most  of  the  nitrates  are  poisonous  when  taken 
internally  in  sufficiently  large  doses,  their  action  seems  to  be  due  rather  to 
the  metal  than  to  the  acid  radical.  Nitric  acid  itself  is  one  of  the  most  powerful 
of  corrosives. 

Any  animal  tissue  with  which  the  concentrated  acid  comes  in  contact  is 
rapidly  disintegrated.  A  yellow  stain,  afterward  turning  to  dirty  brownish,  or, 
if  the  action  be  prolonged,  an  eschar,  is  formed.  When  taken  internally,  its 
action  is  the  same  as  upon  the  skin,  but  owing  to  the  more  immediately  impor- 
tant function  of  the  parts,  is  followed  by  more  serious  results  (unless  a  large 
cutaneous  surface  is  destroyed). 

The  symptoms  following  its  ingestion  are  the  same  as  those  produced  by  the 
other  mineral  acids,  except  that  all  parts  with  which  the  acid  has  come  in 
contact,  including  vomited  shreds  of  mucous  membrane,  are  colored  yellow. 
The  treatment  is  the  same  as  that  indicated  when  H2SO4  or  HC1  have  been  taken, 
i..e.,  neutralization  of  the  corrosive  by  magnesia  or  soap,  and  dilution. 

PHOSPHORUS. 

Symbol=P — Atomic  weight=%\  (International=31.Q4) — Molecu- 
lar iveight=124:  (PJ—Sp.  gr.  of  vapor— 4.2904  A. 

Occurrence. — Only  in  combination ;  in  the  mineral  and  vegetable 
worlds  as  phosphates  of  Ca,  Mg,  Al,  Pb,  K,  Na.  In  the  animal 
kingdom  as  phosphates  of  Ca,  Mg,  K  and  Na,  and  in  organic  com- 
bination. 

Preparation. — From  bone-ash  in  which  it  occurs  as  tricalcic 
phosphate.  Three  parts  of  bone-ash  are  digested  with  2  parts  of 
strong  H2S04,  diluted  with  20  volumes  H20,  when  insoluble  calcic 
sulphate  and  the  soluble  monocalcic  phosphate,  or  "superphosphate," 
are  formed: 

Ca3  (P04)  2+2H2S04=CaH4  (P04)  2+2CaS04 
The  solution  of  superphosphate  is  filtered  off  and  evaporated,  the 


104  TEXT-BOOK   OF   CHEMISTRY 

residue  is  mixed  with  about  one-fourth  its  weight  of  powdered  char- 
coal and  sand,  and  the  mixture  heated,  first  to  redness,  finally  to  a 
white  heat,  in  earthenware  retorts,  whose  beaks  dip  under  water  in 
suitable  receivers.  During  the  first  part  of  the  heating  the  mono- 
calcic  phosphate  is  converted  into  metaphosphate : 
CaH4(P04)2=Ca(P03)2+2H20, 

which  is  in  turn  reduced  by  the  charcoal,  with  formation  of  carbon 
monoxide  and  liberation  of  phosphorus,  while  the  calcium  is  com- 
bined as  silicate : 

2Ca(P03)2+2Si02+5C2=2CaSi03+10CO+P4 

A  direct  electric  process  has,  in  great  part,  replaced  the  above 
industrially.  A  mixture  of  phosphate,  carbon  and  flux  is  heated  in  a 
closed  electric  furnace  provided  with  a  condenser.  The  process  is 
continuous  and  avoids  the  use  of  H2S04. 

The  crude  product  is  purified  by  fusion,  first  under  a  solution  of 
bleaching  powder,  next  under  ammoniacal  H20,  and  finally  under 
water  containing  a  small  quantity  of  H2S04  and  potassium  dichro- 
mate.  It  is  then  strained  through  leather  and  cast  into  sticks  under 
warm  H20. 

Properties. — Physical. — Phosphorus  is  capable  of  existing  in  four 
allotropic  forms: 

(1)  Ordinary,  or  yellow  variety,  in  which  it  usually  occurs  in  com- 
merce. This  is  a  yellowish,  translucid  solid,  of  the  consistency  of 
wax.  Below  0°  it  is  brittle;  it  fuses  at  44.3°;  and  boils  at  290° 
in  an  atmosphere  not  capable  of  acting  upon  it  chemically.  Its 
vapor  is  colorless;  sp.  gr.=4.5A — 65  H  at  1040°.  It  volatilizes  below 
its  boiling  point,  and  H20  boiled  upon  it  gives  off  steam  charged 
with  its  vapor.  Exposed  to  air  it  gives  off  white  fumes  and  produces 
ozone.  It  is  luminous  in  the  dark.  It  is  insoluble  in  H20 ;  sparingly 
soluble  in  alcohol,  more  soluble  in  ether ;  soluble  in  carbon  disulphide, 
and  in  the  fixed  and  volatile  oils.  It  crystallizes  on  evaporation  of  its 
solutions  in  octahedrae  or  dodecahedrae.  Sp.  gr.  1.83  at  10°. 

(2)  White  phosphorus  is  formed  as  a  white,  opaque  pellicle  upon 
the  surface  of  the  ordinary  variety,  when  this  is  exposed  to  light 
under  aerated  H20.    Sp.  gr.  1.515  at  15°.    When  fused  it  reproduces 
ordinary  phosphorus  without  loss  of  weight. 

(3)  Black  variety  is  formed  when  ordinary  phosphorus  is  heated 
to  70°  and  suddenly  cooled. 

(4)  Red  variety  is  produced  from  the  ordinary  by  maintaining  it 
at  from  240°  to  280°  for  two  or  three  days,  in  an  atmosphere  of 
carbon  dioxide;  and,  after  cooling,  washing  out  the  unaltered  yellow 
phosphorus  with  carbon  disulphide.     It   is  also   formed  upon   the 
surface  of  the  yellow  variety,  when  it  is  exposed  to  direct  sunlight. 

It  is  a  reddish,  odorless,  tasteless  solid,  which  does  not  fume  in 
air,  nor  dissolve  in  the  solvents  of  the  yellow  variety.  Sp.  gr.  2.1. 


PHOSPHORUS  105 

Heated  to  500°  with  lead,  in  the  absence  of  air,  it  dissolves  in  the 
molten  metal,  from  which  it  separates  on  cooling  in  violet-black, 
rhombohedral  crystals,  of  sp.  gr.  2.34.  If  prepared  at  250°  it  fuses 
below  that  temperature,  and  at  260°  is  transformed  into  the  yellow 
variety,  which  distils.  The  crystalline  product  does  not  fuse.  It  is 
not  luminous  at  ordinary  temperatures. 

Chemical. — The  most  prominent  property  of  P  is  the  readiness 
with  which  it  combines  with  0.  The  yellow  variety  ignites  and 
burns  with  a  bright  flame  if  heated  in  air  to  60°,  or  if  exposed  in  a 
finely-divided  state  to  air  at  the  ordinary  temperature;  with  forma- 
tion of  P203;  P205;  H3P03,  or  H3P04,  according  as  0  is  present 
in  excess  or  not,  and  according  as  the  air  is  dry  or  moist.  The  tem- 
perature of  ignition  of  yellow  P  is  so  low  that  it  must  be  preserved 
under  boiled  water.  By  directing  a  current  of  0  upon  it,  P  may 
be  burned  under  H20,  heated  above  45°.  The  red  variety  combines 
with  0  much  less  readily,  and  may  be  kept  in  contact  with  air 
without  danger. 

The  luminous  appearance  of  yellow  P  is  said  to  be  due  to  the 
formation  of  ozone.  It  does  not  occur  in  pure  0  at  the  ordinary 
temperature,  nor  in  air  under  pressure,  nor  in  the  absence  of  mois- 
ture, nor  in  the  presence  of  minute  quantities  of  carbon  disulphide, 
oil  of  turpentine,  alcohol,  ether,  naphtha,  and  many  gases. 

Yellow  phosphorus  burns  in  Cl  with  formation  of  PC13  or  PC15, 
according  as  P  or  Cl  is  present  in  excess.  Both  yellow  and  red 
varieties  combine  directly  with  Cl,  Br,  and  I. 

Phosphorus  is  not  acted  on  by  HC1  or  cold  H2S04.  Hot  H2S04 
oxidizes  it  with  formation  of  phosphorous  acid  and  sulphur  dioxide: 
P4+6H2S04=4H3P03+6S02. 

Nitric  acid  oxidizes  it  violently  to  phosphoric  acid  and  nitrogen  di- 
and  tetr-oxides: 

12HN03+P4=4H3P04+4N204+4NO. 

Phosphorus  is  a  reducing  agent.  When  immersed  in  cupric  sul- 
phate solution,  it  becomes  covered  with  a  coating  of  metallic  copper. 
In  silver  nitrate  solution  it  produces  a  black  deposit  of  silver 
phosphide. 

The  principal  uses  of  phosphorus  are  in  making  matches,  rat 
paste  and  phosphor  bronze. 

Toxicology. — The  red  variety  differs  from  the  other  allotropic  forms  of 
phosphorus  in  not  being  poisonous,  probably  owing  to  its  insolubility,  and  in 
being  little  liable  to  cause  injury  by  burning. 

The  burns  produced  by  yellow  phosphorus  are  more  serious  than  a  like 
destruction  of  cutaneous  surface  by  other  substances.  A  burning  fragment  of 
P  adheres  tenaciously  to  the  skin,  into  which  it  burrows.  One  of  the  products 
of  the  combustion  is  metaphosphoric  acid  (q.v.)  which,  being  absorbed,  gives 
rise  to  true  poisoning.  Burns  by  P  should  be  washed  immediately  with  dilute 
Javelle  water,  liquor  sodse  chlorinatae,  or  solution  of  chloride  of  lime.  Yellow 


106  TEXT-BOOK   OF   CHEMISTRY 

P  should  never  be  allowed  to  come  in  contact  with  the  skin,  except  under  cold 
water. 

Yellow  P  is  one  of  the  most  insidious  of  poisons.  It  is  taken  or  adminis- 
tered usually  as  "  ratsbane  "  or  match-heads.  The  former  is  frequently  starch 
paste,  charged  with  phosphorus;  the  latter,  in  the  ordinary  sulphur  match,  a 
mixture  of  potassium  chlorate,  very  fine  sand,  phosphorus,  and  a  coloring  matter. 
The  symptoms  in  acute  phosphorus-poisoning  appear  with  greater  or  less  rapidity, 
according  to  the  dose,  and  the  presence  or  absence  in  the  stomach  of  substances 
which  favor  its  absorption.  Their  appearance  may  be  delayed  for  days,  but  as  a 
rule  they  appear  within  a  few  hours.  A  disagreeable  garlicky  taste  in  the 
mouth,  and  heat  in  the  stomach  are  first  observed,  the  latter  gradually  de- 
veloping into  a  burning  pain,  accompanied  by  vomiting  of  dark-colored  matter, 
which,  when  shaken  in  the  dark,  is  phosphorescent;  low  temperature  and  dilata- 
tion of  the  pupils.  In  some  cases,  death  follows  at  this  point  suddenly,  without 
the  appearance  of  any  further  marked  symptoms.  Usually,  however,  the  patient 
rallies,  seems  to  be  doing  well,  until,  suddenly,  jaundice  makes  its  appearance, 
accompanied  by  retention  of  urine,  and  frequently  delirium,  followed  by  coma 
and  death. 

There  is  no  known  chemical  antidote  to  phosphorus.  The  treatment  is, 
therefore,  limited  to  the  removal  of  the  unabsorbed  portions  of  the  poison  by 
the  action  of  an  emetic,  zinc  or  copper  sulphate,  or  apomorphine,  as  expeditiously 
as  possible,  and  the  administration  of  French  oil  of  turpentine — the  older  the 
oil  the  better — as  a  physiological  antidote.  The  use  of  fixed  oils  or  fats  is  to  be 
avoided,  as  they  favor  the  absorption  of  the  poison,  by  their  solvent  action.  The 
prognosis  is  very  unfavorable. 

Analysis. — When,  after  a  death  supposed  to  be  caused  by  phosphorus, 
chemical  evidence  of  the  existence  of  the  poison  in  the  body,  etc.,  is  desired, 
the  investigation  must  be  made  as  soon  after  death  as  possible,  for  the  reason 
that  the  element  is  rapidly  oxidized,  and  the  detection  of  the  higher  stages  of 
oxidation  of  phosphorus  is  of  no  value  as  evidence  of  the  administration  of  the 
element,  because  they  are  normal  constituents  of  the  body  and  of  the  food. 

Chronic  phosphorus  poisoning,  or  Lucifer  disease,  occurs  among  operatives 
engaged  in  the  dipping,  drying,  and  packing  of  phosphorus  matches.  Those 
engaged  in  the  manufacture  of  phosphorus  itself  are  not  so  affected.  Sickly 
women  and  children  are  most  subject  to  it.  The  cause  of  the  disease  has  been 
ascribed  to  the  presence  of  arsenic,  and  to  the  formation  of  oxides  of  phos- 
phorus, and  of  ozone.  The  progress  of  the  disorder  is  slow,  and  its  culminating 
manifestation  is  the  destruction  of  one  or  both  maxillae  by  necrosis. 

The  frequency  of  the  disease  may  be  in  some  degree  diminished  by  thorough 
ventilation  of  the  shop,  by  frequent  washing  of  the  face  and  mouth  with  a 
weak  solution  of  sodium  carbonate,  by  exposing  oil  of  turpentine  in  saucers  in 
the  workshops,  and  particularly  by  keeping  the  teeth  in  repair.  None  of  these 
methods,  however,  effect  a  perfect  prevention,  which  can  only  be  attained  by  the 
substitution  of  the  red  variety  of  phosphorus  for  the  yellow  in  this  industry. 

Hydrogen  Phosphides. — Gaseous  hydrogen  phosphide — Phos- 
phine. — PH3 — 34 — a  colorless  gas,  having  a  strong  alliaceous  odor, 
which  is  obtained  pure  by  decomposing  phosphonium  iodide,  PH4I, 
with  H20.  Mixed  with  H  and  vapor  of  P2H4,  it  is  produced,  as  a 
spontaneously  inflammable  gas,  by  the  action  of  hot,  concentrated 
solution  of  potassium  hydroxide  on  P,  or  by  decomposition  of  calcium 
phosphide  by  H20.  It  is  highly  poisonous.  After  death,  the  blood 
is  found  to  be  of  a  dark  violet  color,  and  also  to  have,  in  a  great 
measure,  lost  its  power  of  absorbing  oxygen. 


PHOSPHORUS  107 

Liquid  hydrogen  phosphide — P2H4 — 66 — is  the  substance  whose  vapor 
communicates  to  PH3  its  property  of  igniting  on  contact  with  air.  It  is 
separatee!  by  passing  the  spontaneously  inflammable  PH3  through  a  bulb  tube, 
surrounded  by  a  freezing  mixture. 

It  is  a  colorless,  heavy  liquid,  which  is  decomposed  by  exposure  to  sunlight, 
or  to  a  temperature  of  30°. 

Solid  hydrogen  phosphide — P4H2 — 126 — is  a  yellow  solid,  formed  when 
P2H4  is  decomposed  by  sunlight.  It  is  not  phosphorescent  and  only  ignites 
at  160°. 

Compounds  of  Phosphorus  with  the  Halogens — Phosphorus  Trichloride 
— PC13 — 137.5 — is  obtained  by  heating  P  in  a  limited  supply  of  Cl.  It  is  a  color- 
less liquid;  sp.  gr.  1.61;  has  an  irritating  odor;  fumes  in  air;  boils  at  76°. 
Water  decomposes  it  with  formation  of  H3P03  and  HC1. 

Phosphorus  Pentachloride — PC15 — 208.5 — is  formed  when  P  is  burnt  in 
excess  of  Cl.  It  is  a  light  yellow,  crystalline  solid:  gives  off  irritating  fumes; 
and  is  decomposed  by  H2O. 

Phosphorus  Oxychloride — POC13 — 153.5 — is  formed  by  the  action  of  a 
limited  quantity  of  H20  on  the  pentachloride: 

PC15+H20=POC13+2HC1. 

It  is  a  colorless  liquid:  sp.  gr.  1.07;  boils  at  110°,  and  solidifies  at  — 10°. 

Oxides  of  Phosphorus. — Two  are  known:  P203  and  P205. 

Phosphorus  Trioxide. — Phosphorous  anhydride,  Phosphorous 
oxide — P203 — 110 — is  formed  when  P  is  burned  in  a  very  limited 
supply  of  perfectly  dry  air,  or  0.  It  is  white,  flocculent  solid,  which, 
on  exposure  to  air,  ignites  by  the  heat  developed  by  its  union  with 
H.,0  to  form  phosphorous  acid. 

Phosphorus  Pentoxide. — Phosphoric  anhydride,  Phosphoric  oxide 
— P205 — 142 — is  formed  when  P  is  burned  in  an  excess  of  dry  0.  It 
is  a  white,  flocculent  solid,  which  has  almost  as  great  a  tendency  to 
combine  with  H20  as  has  P203.  It  absorbs  moisture  rapidly,  deli- 
quescing to  a  highly  acid  liquid,  containing,  not  phosphoric,  but 
metaphosphoric  acid.  It  is  used  as  a  drying  agent. 

Phosphorus  Acids. — Six  oxyacids  of  phosphorus  are  known: 

/O— H  /o— H 

Hypophosphorous  acid:    0=P — H  0=P— 0 — H 

\  H  \ 

Pyrophosphoric  acid:  \O 

/O— H                                             0=P— 0— H 
Phosphorous  acid:  O=P — O — H  \O H 

\H 

/O— H 

/O— H  0=P— 0— H 

Phosphoric  acid:  0=P— O — H  „         ,       ,      .         .,  \ 

\O— H  Hypophosphoric   acid:  ^,O 

P— O— H 
/O— H  \0— H 

Metaphosphoric  acid:     O=P=O 

Only  those  H  atoms  which  are  connected  with  the  P  atoms 
through  0  atoms  are  basic.  Hence  H3P02  is  monobasic;  H3P03  is 
dibasic ;  H3P04  is  tribasic ;  H4P207  is  tetrabasic ;  HP02  is  monobasic, 
and  H4P20C  is  tetrabasic. 


108  TEXT-BOOK    OF    CHEMISTRY 

Hypophosphorous  Acid. — H3P02 — 66 — is  a  crystalline  solid,  or, 
more  usually,  a  strongly  acid,  colorless  syrup.  It  is  oxidized  by  air 
to  a  mixture  of  H3P03  and  H3P04. 

The  acidum  hypophosphorosum  (U.  S.  P.)  is  an  aqueous  solution 
containing  not  less  than  30  per  cent,  nor  more  than  32  per  cent,  of 
H3P02;  and  the  acidum  hypophosphorosum  dilutum  (U.  S.  P.)  is  an 
aqueous  solution  containing  not  less  than  9.5  per  cent,  nor  more  than 
10.5  per  cent,  of  H3P02. 

The  hypophosphites,  as  well  as  the  free  acid,  are  powerful  re- 
ducing agents. 

Phosphorous  Acid — H3P03 — 82 — is  formed  by  decomposition  of 
phosphorus  trichloride  by  water: 

PC13+3H20=3HC1+H3P03 

It  is  a  highly  acid  syrup,  is  decomposed  by  heat,  and  is  a  strong 
reducing  agent. 

Phosphoric  Acid — Orthophosphoric  acid — Acidum  phosphoricum 
(U.  S.  P.) — H3P04 — 98 — does  not  occur  free  in  nature,  but  is  widely 
disseminated  in  combination,  in  the  phosphates,  in  the  three  king- 
doms of  nature. 

It  is  prepared:  (1)  By  converting  bone  phosphate,  Ca3(P04)2  into 
the  corresponding  lead  or  barium  salt  Pb3(P04)2  or  Ba3(P04)2,  and 
decomposing  the  former  by  H2S,  or  the  latter  by  H2S04. 

(2)  By  oxidizing  P  by  dilute  HN03,  aided  by  heat: 

3P4+20HN03+8H20=20NO+12H3P04 

The  operation  should  be  conducted  with  caution,  and  heat  gradually 
applied  by  the  sand  bath.  It  is  best  to  use  red  phosphorus. 

The  concentrated  acid  is  a  colorless,  transparent,  syrupy  liquid; 
still  containing  H20,  which  it  gives  off  on  exposure  over  H2S04,  leav- 
ing the  pure  acid,  in  transparent,  deliquescent,  prismatic  crystals. 
It  is  decomposed  by  heat  to  form,  first,  pyrophosphoric  acid,  then 
metaphosphoric  acid.  It  is  tribasic. 

If  made  from  arsenical  phosphorus,  and  commercial  phosphorus 
is  arsenical  unless  made  by  the  electrolytic  method  (p.  20),  it  is 
contaminated  with  arsenic  acid,  whose  presence  may  be  recognized  by 
Marsh's  test  (q.  v.).  The  acid  should  not  respond  to  the  indigo  and 
ferrous  sulphate  tests  for  HN03. 

The  acidum  phosphoricum  (U.  S.  P.)  contains  not  less  than  85 
per  cent,  nor  more  than  88  per  cent,  of  H3P04;  and  the  acidum 
phosphoricum  dilutum  (U.  S.  P.)  contains  not  less  than  9.5  per  cent, 
nor  more  than  10.5  per  cent,  of  H3P04. 

Ortho-acids  are  those  in  which  the  number  of  hydroxyls  equals 
the  valence  of  the  acidulous  elements.  Thus  orthophosphoric  acid 
is  P(OH)r, ;  orthocarbonic  acid,  C(OH)4.  Sometimes,  as  in  the 
case  of  phosphorus,  when  this  acid  is  not  known,  that  in  which  the 


PHOSPHORUS  109 

number  of  Tiydroxyls  most  nearly  equals  the  valence  of  the  acidulous 
element  .is,  improperly,  called  the  ortho-acid. 

Phosphates. — Phosphoric  acid  being  tribasic,  the  phosphates  have 
the  composition  M'H,P04 ;  M'9HP04 ;  M'3P04;  M"(H2P04)2; 
M"2(HP04)2;  M"3(PO4)2;  M"M'P04 ;  and  M"'P04.  The  mono- 
metallic salts  are  all  soluble  and  are  strongly  acid.  Of  the  dimetallic 
salts,  those  of  the  alkali  metals  only  are  soluble  and  their  solutions 
are  faintly  alkaline;  the  others  are  unstable,  and  exhibit  a  marked 
tendency  to  transformation  into  monometallic  or  trimetallic  salts. 
The  normal  phosphates  of  the  alkali  metals  are  the  only  soluble  tri- 
metallic phosphates.  Their  solutions  are  strongly  alkaline,  and  they 
are  decomposed  even  by  weak  acids: 

Na3P04        -f  C03H2  Na2HP04  -f  NaHCO, 

Trisodic  Carbonic  Disodic  Monosodic 

phosphate.  acid.  phosphate.  carbonate. 

All  the  monometallic  phosphates,  except  those  of  the  alkali  metals, 
are  decomposed  by  ammonium  hydroxide,  with  precipitation  of  the 
corresponding  trimetallic  salt. 

Analytical  Characters. —  (1)  With  ammoniacal  solution  of  silver 
nitrate,  a  yellow  precipitate.  (2)  With  solution  of  ammonium 
molybdate  in  HN03,  a  yellow  precipitate.  (3)  With  magnesia  mix- 
ture,* a  white,  crystalline  precipitate,  soluble  in  acids,  insoluble  in 
ammonium  hydroxide. 

Pyrophosphoric  Acid — H4P207 — 178. — When  phosphoric  acid  (or 
hydro-disodic  phosphate)  is  maintained  at  213°,  two  of  its  molecules 
unite,  with  the  loss  of  the  elements  of  a  molecule  of  water:  2H3P04= 
H20-f  H4P207,  to  form  pyrophosphoric  acid. 

Metaphosphoric  Acid — Glacial  phosphoric  acid — HP03 — 80 — is 
formed  by  heating  H3P04  or  H4P207  to  near  redness :  H3P04=HP03 
+H20 ;  or  H4P207=2HP03+H20.  It  is  usually  obtained  from  bone 
phosphate;  this  is  first  converted  into  ammonium  phosphate,  which 
is  then  subjected  to  a  red  heat. 

It  is  a  white,  glassy,  transparent  solid,  odorless  and  acid  in  taste 
and  reaction.  Slowly  deliquescent  in  air,  it  is  very  soluble  in  H20, 
although  the  solution  takes  place  slowly,  and  is  accompanied  by  a 
peculiar  crackling  sound.  In  constitution  and  basicity  it  resembles 
HN03. 

Hypophosphoric  Acid — H4P206 — 162. — When  phosphorus  is  ex- 
posed to  moist  air  a  strongly  acid  liquid  is  slowly  formed,  known  as 
phosphatic  acid.  This  is  a  mixture  of  phosphorous,  phosphoric  and 
hypophosphoric  acids.  The  last  named  is  separated  from  the  others 
by  taking  advantage  of  the  sparing  solubility  of  its  acid  sodium  salt ; 
this  is  then  converted  into  the  lead  salt,  which  is  decomposed  by  H2S, 

*  Made  by  dissolving  11  pts.  crystallized  magnesium  chloride  and  28  pts.  ammonium 
chloride  in  130  pts.  water,  adding  70  pts.  dilute  ammonium  hydroxide  (sp.  gr.  0.96)  and  filter- 
ing after  two  days. 


110  TEXT-BOOK   OF   CHEMISTRY 

and  the  liberated  acid  concentrated.  It  has  not  been  crystallized. 
It  is  quite  stable  at  the  ordinary  temperature,  but  slowly  decomposes 
to  a  mixture  of  phosphorous  and  pyrophosphoric  acids.  It  is  quadri- 
basic.  It  may  be  considered  as  formed  by  the  union  of  a  molecule 
of  phosphoric  acid  and  one  of  phosphorous  acid,  with  loss  of  H20: 
H3P04+H3P03=H4P206+H20. 

ARSENIC. 

Symbol—  As  —  Atomic  weight=15   (International^  A.  96)  —  Molec- 
ular weight=30Q   (As4)  —  Sp.  gr.  of  solid;  crystalline—  5.75,  amor- 
;  of  vapor=W.6  A  at  860°. 


Occurrence.  —  Free  in  small  quantity  ;  in  combination  as  arsenides 
of  Fe,  Co,  and  Ni,  but  most  abundantly  in  the  sulphides,  orpiment 
and  realgar,  and  in  arsenical  iron  pyrites,  or  mispickel. 

Preparation.  —  (1)  By  heating  mispickel  in  clay  cylinders,  which 
communicate  with  sheet  iron  condensing  tubes. 

(2)  By  heating  a  mixture  of  arsenic  trioxide  and  charcoal;  and 
purifying  the  product  by  resublimation  : 

2As203+6C=6CO+As4 

Properties.  —  Physical.  —  A  brittle,  crystalline,  steel-gray  solid, 
having  a  metallic  luster,  or  a  dull,  black,  amorphous  powder.  At  the 
ordinary  pressure,  and  without  contact  of  air,  it  volatilizes  without 
fusion  at  180°;  under  strong  pressure  it  fuses  at  a  dull  red  heat. 
Its  vapor  is  yellowish,  and  has  the  odor  of  garlic.  It  is  insoluble 
in  H20,  and  in  other  liquids  unless  chemically  altered. 

Chemical.  —  Heated  in  air  it  is  converted  into  the  trioxide,  and 
ignites  somewhat  below  a  red  heat.  In  0  it  burns  with  a  brilliant, 
bluish-white  light.  In  dry  air  it  is  not  altered,  but  in  the  presence 
of  moisture  its  surface  becomes  tarnished  by  oxidation.  In  H20  it  is 
slowly  oxidized,  a  portion  of  the  oxide  dissolving  in  the  water.  It 
combines  readily  with  Cl,  Br,  I,  and  S,  and  with  most  of  the  metals. 
With  H  it  only  combines  when  that  element  is  in  the  nascent  state. 
Warm,  concentrated  H2S04  is  decomposed  by  As,  with  formation  of 
S02,  As203,  and  H20.  Nitric  acid  is  readily  decomposed,  giving  up 
its  0  to  the  formation  of  arsenic  acid.  With  hot  HC1,  arsenic  tri- 
chloride is  formed.  When  fused  with  potassium  hydroxide,  arsenic 
is  oxidized,  H  is  given  off,  and  a  mixture  of  potassium  arsenite  and 
arsenide  remains,  which  by  greater  heat  is  converted  into  arsenic, 
which  volatilizes,  and  potassium  arsenate,  which  remains. 

Elementary  arsenic  enters  into  the  composition  of  fly  poison  and  of 
shot,  and  is  used  in  the  manufacture  of  certain  pigments  and  fire- 
works. 

Compounds  of  Arsenic  and  Hydrogen.  —  Two  are  known:  the 
solid  As2H2  (  ?)  and  the  gaseous  AsH3. 


ARSENIC  111 

Hydrogen  Arsenide — Arsine — Arseniuretted  hydrogen — AsH3 — 
Molecular  weight =18 — Sp.  #r.=2.695  A. 

Formation. —  (1)  By  the  action  of  dilute  HC1  or  H2S04  upon  the 
arsenides  of  Zn  and  Sn.  This  is  practically  the  same  as  2,  nascent 
hydrogen  being  formed  by  the  action  of  the  metal  upon  the  acid. 

(2)  Whenever  a  reducible  compound  of  arsenic  is  in  presence  of 
nascent  hydrogen.     (See  Marsh  test.) 

(3)  By  the  action  of  H20  upon  the  arsenides  of  the  alkali  metals. 

(4)  By  the  action  of  hot  solution  of  potassium  hydroxide  upon 
reducible  compounds  of  As  in  the  presence  of  zinc. 

Properties. — Physical. — A  colorless  gas;  having  a  strong  allia- 
ceous odor;  soluble  in  5  vols.  of  H20,  free  from  air. 

Chemical.-. — It  is  neutral  in  reaction.  In  contact  with  air  and 
moisture  its  H  is  slowly  removed  by  oxidation,  and  elementary  As 
deposited.  It  is  also  decomposed  into  its  elements  by  the  passage 
through  it  of  luminous  electric  discharges;  and  when  subjected  to  a 
red  heat.  It  is  acted  on  by  dry  O  at  ordinary  temperatures  with  the 
formation  of  a  black  deposit,  which  is  at  first  solid  hydrogen  arsenide, 
later  elementary  As.  A  mixture  of  As  H3  and  0,  containing  3  vols. 
0  and  2  vols.  AsH3,  explodes  when  heated,  forming  As203  and  H20. 
If  the  proportion  of  0  be  less,  elementary  As  is  deposited. 

The  gas  burns  with  a  greenish  flame,  from  which  a  white  cloud  of 
arsenic  trioxide  arises.  A  cold  surface,  held  above  the  flame,  becomes 
coated  with  a  white,  crystalline  deposit  of  the  oxide.  If  the  flame  is 
cooled  by  the  introduction  of  a  cold  surface  into  it,  the  H  alone  is 
oxidized,  and  elementary  As  is  deposited.  Chlorine  decomposes  the 
gas  explosively,  with  formation  of  HC1  and  arsenic,  or  arsenic  tri- 
chloride, if  the  Cl  is  in  excess.  In  the  presence  of  H20,  arsenous  and 
arsenic  acids  are  formed.  Bromine  and  iodine  behave  similarly,  but 
with  less  violence. 

All  oxidizing  agents  decompose  it  readily;  H20  and  arsenic  tri- 
oxide being  formed  by  the  less  active  oxidants,  and  H20  and  arsenic 
acid  by  the  more  active.  Solid  potassium  hydroxide  decomposes  the 
gas  partially,  and  becomes  coated  with  a  dark  deposit,  which  seems 
to  be  elementary  arsenic.  Solutions  of  the  alkaline  hydroxides  absorb 
and  decompose  it;  H  is  given  off  and  an  alkaline  arsenite  remains 
in  the  solution.  Many  metals,  when  heated  in  H3As,  decompose  it 
with  formation  of  a  metallic  arsenide  and  liberation  of  hydrogen. 
Solution  of  silver  nitrate  is  reduced  by  it;  elementary  silver  is  de- 
posited, and  the  solution  contains  silver  arsenite. 

Although  H2S  and  H3As  decompose  each  other  to  a  great  extent, 
with  formation  of  arsenic  trisulphide,  in  the  presence  of  air,  the  two 
gases  do  not  act  upon  each  other  at  the  ordinary  temperature,  even 
in  the  direct  sunlight,  either  dry  or  in  the  presence  of  H20,  when  air 
is  absent.  Hence  in  making  H2S  for  use  in  toxicological  analysis, 
materials  free  from  As  must  be  used ;  or  the  H2S  must  be  purified. 


112  TEXT-BOOK   OF   CHEMISTRY 

Compounds  of  Arsenic  with  the  Halogens. — Arsenic  Trichloride — 
AsCIj — 181.5.— Obtained  by  distilling  a  mixture  of  As2O3,  H2SO«,  and  NaCl,  using 
a  well-cooled  receiver. 

It  is  a  colorless  liquid,  boils  at  134°,  fumes  when  exposed  to  the  air,  and 
volatilizes  readily  at  temperatures  below  its  boiling  point.  Its  formation  must 
be  avoided  in  processes  for  the  chemico-legal  detection  of  arsenic,  lest  it  In- 
volatilized  and  lost.  It  is  formed  by  the  action  of  HC1,  even  when  comparatively 
dilute,  upon  As2O3  at  the  temperature  of  the  water-bath;  but,  if  potassium 
chlorate  be  added,  the  trioxide  is  oxidized  to  arsenic  acid,  and  the  formation 
of  the  chloride  thus  prevented.  Arsenic  trioxide,  when  fused  with  sodium  nitrate, 
is  converted  into  sodium  arsenate,  which  is  not  volatile.  If,  however,  small 
quantities  of  chlorides  be  present,  AsCl3  is  formed.  It  is  highly  poisonous. 

Arsenic  Triodide — Arsenii  lodidum,  U.  S.  P. — AsI3 — 456. — Formed  by 
adding  As  to  a  solution  of  I  in  carbon  bisulphide,  or  by  fusing  together  As  and 
I  in  proper  proportions.  A  brick-red  solid,  fusible  and  volatile.  Soluble  in  a 
large  quantity  of  H2O.  Decomposed  by  a  small  quantity  of  H20  into  HI,  As2O8, 
H20  and  a  residue  of  AsI8. 

Compounds  of  Arsenic  and  Oxygen. — Two  are  known:  As,0:, 
and  As20,j. 

Probably  the  gray  substance  formed  by  the  action  of  moist  air  on 
elementary  arsenic  is  a  lower  oxide. 

Arsenic  Trioxide — Arsenous  anhydride — Arsenous  oxide — White 
arsenic — Arsenic — As203— 198. 

Preparation. —  (1)  By  roasting  the  native  sulphides  of  arsenic  in 
a  current  of  air: 

2As2S3+902=6S02+2As203 

(2)  By  burning  arsenic  in  air  or  oxygen. 

Properties. — Physical. — It  occurs  in  three  forms:  crystallized  or 
"powdered,"  vitreous,  and  porcelainous.  When  freshly  fused,  it  ap- 
pears in  colorless  or  faintly  yellow,  translucent,  vitreous  masses, 
having  no  visible  crystalline  structure.  Shortly,  however,  these 
masses  become  opaque  upon  the  surface,  and  present  the  appearance 
of  porcelain.  This  change  slowly  progresses  toward  the  center  of  the 
mass,  which,  however,  remains  vitreous  for  a  long  time.  When 
arsenic  trioxide  is  sublimed,  if  the  vapors  are  condensed  upon  a  cool 
surface,  it  is  deposited  in  the  form  of  brilliant  octahedral  crystals, 
which  are  larger  and  more  perfect  the  nearer  the  temperature  of  the 
condensing  surface  is  to  180°.  When  sublimed  under  slightly  in- 
creased pressure,  or  in  an  atmosphere  of  S02,  right  rhombic  prisms 
occur  among  the  octahedra.  It  is  therefore  dimorphous.  The  crystal- 
line variety  may  be  converted  into  the  vitreous,  by  keeping  it  for 
some  time  at  a  temperature  near  its  point  of  volatilization. 

Although  As203  is  heavier  than  water,  when  thrown  upon  that 
liquid  a  large  part  of  the  crystalline  powder  floats,  and  a  part  of  that 
which  sinks  at  first  subsequently  rises.  This  is  due  to  adhesion  of 
air  to  the  particles  of  the  solid.  The  same  phenomenon  renders  the 


ARSENIC  113 

solution  of  As203  in  water  slow  and  irregular.  The  vitreous  variety 
is  more- readily  soluble  than  the  crystalline.  The  taste  of  arsenic 
trioxide  in  solution  is  very  faint,  at  first  sweetish,  afterward  very 
slightly  metallic.  The  solid  is  almost  tasteless.  It  is  odorless.  In 
aqueous  solution  .it  has  a  faintly  acid  reaction.  The  sp.  gr.  of  the 
vitreous  variety  is  3.785 ;  that  of  the  crystalline,  3.689. 

Chemical. — Its  solutions  are  acid  in  reaction,  and  probably  contain 
the  true  arsenous  acid,  H3As03.  They  are  neutralized  by  bases,  with 
formation  of  arsenites.  Solutions  of  sodium,  or  potassium  hydroxide, 
or  carbonate  dissolve  it,  with  formation  of  the  corresponding  arsenite. 
It  is  readily  reduced,  with  separation  of  As,  when  heated  with  hydro- 
gen, carbon,  and  potassium  cyanide,  and  at  lower  temperatures  by 
more  active  reducing  agents.  Oxidizing  agents,  such  as  HN03,  the 
chlorine  oxyacids,  chromic  acid,  convert  it  into  arsenic  pentoxide  or 
arsenic  acid.  Its  solution,  acidulated  with  HC1  and  boiled  in  presence 
of  copper,  deposits  on  the  metal  a  gray  film,  composed  of  an  alloy  of 
Cu  and  As. 

Arsenic  Pentoxide — Arsenic  anhydride — Arsenic  oxide — As205 — 
230 — is  obtained  by  heating  arsenic  acid  to  redness.  It  is  a  white, 
amorphous  solid,  which,  when  exposed  to  the  air,  slowly  absorbs 
moisture.  It  is  fusible  at  a  dull  red  heat,  and  at  a  slightly  higher 
temperature  decomposes  to  As203  and  02.  It  dissolves  slowly  in 
H20,  forming  arsenic  acid,  H3As04. 

Arsenic  Acids. — The  oxyacids  of  arsenic  form  a  series,  corre- 
sponding to  that  of  the  oxyacids  of  phosphorus,  except  that  the  hypo- 
arsenous  and  hypoarsenic  acids  are  unknown,  and  pyro-  and  metar- 
senous  acids  are  known  in  their  salts : 

/O— H 

/O— H        Arsenic    acid:        0=zAs— O— H 

Arsenous   acid:  O=As — 0— H  \0 — H 

\H 

/O— H 
/A   — O— H  O=As— 0— H 

/AS  Q TT  V 

Pyroarsenous    acid:     O  Pyroarsenic   acid:  V* 

V     A  in  f 

\ — 
\O— H 


\As__0— H  0=As— O— H 


Metarsenous   acid:        0=As — O — H  /O — H 

Metarsenic  acid:    O=As=0 

Arsenous  Acid. — H3As03 — 126 — exists  in  aqueous  solutions  of 
the  trioxide,  although  it  has  not  been  separated.  Corresponding  to 
it  are  important  salts,  called  arsenites,  which  have  the  general  for- 
mula HM'2As03,  HM"As03,  H4M"(As03)2.  Pyro-  and  metarsenous 
acids  are  only  known  in  combination. 

Arsenic  Acid — Orthoarsenic  acid — H3As04 — 142 — is  obtained  by 
oxidizing  As203  with  HN03  in  the  presence  of  H20 : 

As203+2H20+2HN03=N203+2H3As04 


114  TEXT-BOOK   OF   CHEMISTRY 

A  similar  oxidation  is  also  effected  by  Cl,  aqua  regia,  and  other 
oxidants. 

A  syrupy,  colorless,  strongly  acid  solution  is  thus  obtained,  which, 
at  15°,  becomes  semi-solid,  from  the  formation  of  transparaent  crys- 
tals, containing  1  Aq.  These  crystals,  which  are  very  soluble  and 
deliquescent,  lose  their  Aq  at  100°,  and  form  a  white,  pasty  mass, 
composed  of  minute  white,  anhydrous  needles.  At  higher  tempera- 
tures it  is  converted  into  H4As207,  HAs03,  and  As205.  In  presence 
of  nascent  H  it  is  decomposed  into  H20  and  AsH3.  It  is  reducible 
to  H3As03  by  S02. 

Like  phosphoric  acid,  arsenic  acid  is  tribasic;  and  the  arsenates 
resemble  the  phosphates  in  composition,  and  in  many  of  their  chemi- 
cal and  physical  properties. 

Metarsenic  Acid— HAs03— 124.— At  200  °-206  °H4As207  grad- 
ually loses  H2O  to  form  metarsenic  acid:  H4As207=2HAs03+H20. 
It  forms  white,  pearly  crystals,  which  dissolve  readily  in  H20,  with 
regeneration  of  H3As04.  It  is  monobasic. 

Compounds  of  Arsenic  and  Sulphur. — Arsenic  Bisulphide — Red 
sulphide  of  arsenic — Realgar — Red  orpiment — As2S2 — 214 — occurs  in 
nature,  in  translucent,  ruby-red  crystals.  It  is  also  prepared  by 
heating  a  mixture  of  As203  and  S.  As  so  obtained  it  appears  in 
brick-red  masses. 

It  is  fusible,  insoluble  in  H20,  but  soluble  in  solutions  of  the 
alkaline  sulphides,  and  in  boiling  solution  of  potassium  hydroxide. 

Arsenic  Trisulphide. — Orpiment — Yellow  sulphide  of  arsenic- 
King's  yellow — As2S3 — 246 — occurs  in  nature  in  brilliant  golden 
yellow  flakes.  Obtained  by  passing  H2S  through  an  acid  solution  of 
As203 ;  or  by  heating  a  mixture  of  As  and  S,  or  of  As203  and  S  in 
equivalent  proportions. 

When  formed  by  precipitation,  it  is  a  lemon-yellow  powder,  or  in 
orange-yellow,  crystalline  masses,  when  prepared  by  sublimation. 
Almost  insoluble  in  cold  H20,  but  sufficiently  soluble  in  hot  H20  to 
communicate  to  it  a  distinct  yellow  color.  By  continued  boiling  with 
H20  it  is  decomposed  into  H2S  and  As203.  Insoluble  in  dilute  HC1 ; 
but  readily  soluble  in  solutions  of  the  alkaline  hydroxides,  carbonates, 
and  sulphides.  It  volatilizes  when  heated. 

Nitric  acid  oxidizes  it,  forming  H3As04  and  H2S04.  A  mixture 
of  HC1  and  potassium  chlorate  has  the  same  effect.  It  corresponds 
in  constitution  to  As203,  and  like  it,  may  be  regarded  as  an  an- 
hydride, for  although  thioarsenous  acid,  H3AsS3,  has  not  been  sepa- 
rated, the  thioarsenites,  pyro-  and  meta-thioarsenites  are  well-char- 
acterized compounds. 

Arsenic  Pentasulphide — As2Sr, — 310 — is  formed  by  fusing  a  mix- 
ture of  As2S3  and  S  in  proper  proportions,  and,  by  the  prolonged 
action  of  H,S,  at  low  temperatures,  upon  solutions  of  the  arsenates. 

It  is  a  yellow,  fusible  solid,  capable  of  sublimation  in  absence  of 


ARSENIC  115 

air.     There*   exist   well-defined  thioarsenates,   pyro-   and  meta-thio- 
arsenates. 

Action  of  Arsenical  Compounds  Upon  the  Animal  Economy. 

The  poison  is  usually  taken  by  the  mouth,  but  it  has  also  been  introduced 
by  other  channels;  the  skin,  either  uninjured  or  abraded,  the  rectum,  vagina, 
and  male  urethra.  The  forms  in  which  it  has  been  taken  are :  ( 1 )  Elementary 
arsenic,  which  is  not  poisonous  so  long  as  it  remains  such.  In  contact  with 
water,  or  with  the  saliva,  however,  it  is  converted  into  an  oxide,  which  is  then 
dissolved,  and,  being  capable  of  absorption,  produces  the  characteristic  effects 
of  the  arsenical  compounds.  Certain  fly-papers  and  fly-poisons  contain  As,  a 
portion  of  which  has  been  oxidized  by  the  action  of  air  and  moisture.  (2) 
Hydrogen  arsenide,  the  most  actively  poisonous  of  the  inorganic  compounds  of 
arsenic,  has  been  the  cause  of  several  accidental  deaths;  death  has  followed 
the  inhalation  of  hydrogen,  made  from  zinc  and  sulphuric  acid  contaminated 
with  arsenic.  (3)  Arsenic  trioxide  is  the  compound  most  frequently  used  by 
criminals.  It  has  been  given  by  every  channel  of  entrance  to  the  circulation; 
and  if  given  in  large  quantity,  and  undissolved,  it  may  be  found  in  the 
stomach  after  death,  in  the  form  of  eight-sided  crystals,  more  or  less  worn  by 
the  action  of  the  solvents  with  which  it  has  come  in  contact.  (4)  Potassium 
arsenite,  the  active  substance  in  "  Fowler's  solution,"  has  produced  but  few 
cases  of  fatal  poisoning.  (5)  Sodium  arsenite  is  sometimes  used  to  clean 
metal  vessels;  a  practice  which  has  resulted  in  death  or  serious  illness.  (6) 
Arsenic  acid  and  arsenates- — The  acid  itself  has,  so  far  as  we  know,  been 
directly  fatal  to  no  one.  But  the  cases  of  death  and  illness  which  have  been 
put  to  the  account  of  the  red  aniline  dyes,  are  not  due  to  them  directly,  but 
to  arsenical  residues  remaining  in  them  as  the  result  of  defective  processes  of 
manufacture.  ( 7 )  Sulphides  of  arsenic. — Poisoning  by  these  is  generally  due 
to  the  use  of  orpiment,  introduced  into  articles  of  food  as  a  coloring  matter, 
by  a  combination  of  fraud  and  stupidity,  in  mistake  for  turmeric.  (8)  The 
arsenical  greens. — Scheele's  green,  or  cupric  arsenite,  and  Schweinfurth  green, 
or  cupric  aceto-metarsenite  (the  latter  commonly  known  in  the  United  States  as 
Paris  green,  a  name  applied  in  Europe  to  one  of  the  aniline  pigments ) . 

The  arsenical  pigments  may  also  produce  disastrous  results  by  "accident;" 
by  being  incorporated  in  ornamental  pieces  of  confectionery;  by  being  used  in 
the  coloring  of  textile  fabrics,  from  which  they  may  be  easily  rubbed  off;  from 
their  use  for  the  destruction  of  insects,  and  by  being  used  in  the  manufacture 
of  wall-paper.  Many  instances  of  chronic  or  subacute  arsenical  poisoning  have 
resulted  from  inhabiting  rooms  hung  with  paper  whose  whites,  reds,  or  greens 
were  produced  by  arsenical  pigments.  From  such  paper  the  poison  is  dissemi- 
nated in  the  atmosphere  of  the  room  in  two  ways:  either  as  an  impalpable 
powder,  mechanically  detached  from  the  paper  and  floating  in  the  air,  or  by 
their  decomposition,  and  the  consequent  diffusion  of  volatile  arsenical  com- 
pounds in  the  air. 

The  treatment  in  acute  arsenical  poisoning  is  the  same,  whatever  may  be  the 
form  in  which  the  poison  has  been  taken,  if  it  has  been  taken  by  the  mouth. 
The  first  indication  is  the  removal  of  any  unabsorbed  poison  from  the  alimentary 
canal.  If  vomiting  has  not  occurred  from  the  effects  of  the  toxic,  it  should  be 
induced  by  the  administration  of  apomorphine,  or  zinc  sulphate,  or  by  mechani- 
cal means.  When  the  stomach  has  been  emptied,  the  chemical  antidote  is  to 
be  administered,  with  a  view  to  the  transformation,  in  the  stomach,  of  any  re- 
maining arsenical  compound  into  the  insoluble,  and  therefore  innocuous,  ferrous 
arsenate.  The  U.  S.  P.  gives  an  "  arsenic  antidote,"  ferri  hydroxidum  cum 
magnesii  oxido  (ferric  hydroxide  with  magnesium  oxide):  "Mix  40  cc.  of 


116  TEXT-BOOK   OF    CHEMISTRY 

solution  of  ferric  sulphate  with  125  cc.  of  water,  and  keep  the  liquid  in  a 
large,  well-stoppered  bottle.  Rub  10  gm.  magnesium  oxide  with  cold  water  to  a 
smooth  and  thin  mixture,  transfer  this  to  a  bottle  capable  of  holding  about 
1000  cc.,  fill  it  with  water  to  about  three-fourths  of  its  capacity,  and  keep  it 
tightly  stoppered.  When  the  preparation  is  wanted  for  use,  shake  the  mag- 
nesium oxide  mixture  until  of  a  thin,  creamy  consistence,  slowly  add  to  it  the 
diluted  solution  of  ferric  sulphate,  and  shake  them  together  until  a  uniformly 
smooth  mixture  results."  The  dose  is  about  four  fluid  ounces.  Dialyzed  iron 
may  be  given  when  the  antidote  is  not  obtainable. 

Precautions  to  be  taken  by  the  Physician  in  cases  of  Suspected  Poisoning. 

In  a  case  in  which,  from  the  symptoms,  the  physician  suspects  poisoning 
by  any  substance,  he  should  himself  test  the  urine  or  feces,  or  both,  and  govern 
his  treatment  and  his  actions  toward  the  patient,  and  those  surrounding  the 
patient,  by  the  results  of  his  examination.  Should  the  case  terminate  fatally, 
he  should  at  once  communicate  his  suspicions  to  the  prosecuting  officer,  and 
require  a  post-mortem  investigation,  which  should,  if  at  all  possible,  be  con- 
ducted in  the  presence  of  the  chemist  who  is  to  conduct  the  analysis. 

Cases  frequently  arise  in  which  it  is  impossible  to  bring  the  chemist  upon 
the  ground  in  time  for  the  autopsy.  In  such  cases  the  physician  should  remem- 
ber that  that  portion  of  the  poison  remaining  in  the  alimentary  tract  (we  are 
speaking  of  true  poisons)  is  but  the  residue  of  the  dose  in  excess  of  that  which 
has  been  necessary  to  produce  death;  and,  if  the  processes  of  elimination  have 
been  active,  there  may  remain  no  trace  of  the  poison  in  the  alimentary  canal, 
while  it  still  may  be  detectable  in  the  deeper-seated  organs.  The  poison  may 
also  have  been  administered  by  another  channel  than  the  mouth,  in  which 
event  it  may  not  reach  the  stomach. 

For  these  reasons  it  is  not  sufficient  to  send  the  stomach  alone  for  analysis. 
The  chemist  should  also  receive  the  entire  intestinal  canal,  the  liver,  the 
spleen,  one  or  both  kidneys,  a  piece  of  muscular  tissue  from  the  leg,  the  brain, 
and  any  urine  that  may  remain  in  the  bladder.  The  intestinal  canal  should  be 
removed  and  sent  to  the  chemist  without  having  been  opened,  and  with  liga- 
tures, enclosing  the  contents,  at  the  two  ends  of  the  stomach  and  at  the  lower 
end  of  the  intestine.  The  brain  and  alimentary  canal  are  to  be  placed  in 
separate  jars,  and  the  other  viscera  in  another  jar  together;  the  urine  in  a  vial 
by  itself.  All  of  these  vessels  are  to  be  new  and  clean,  and  are  to  be  closed  by 
new  corks,  or  by  glass  stoppers,  or  covers  ( not  zinc  screw-caps ) ,  which  are 
then  coated  with  paraffin  (not  sealing-wax),  and  so  fastened  with  strings  and 
seals,  that  it  is  impossible  to  open  the  vessels  without  cutting  the  strings  or 
breaking  the  seals.  Any  vomited  matters  are  to  be  preserved.  If  the  physician 
fails  to  observe  these  precautions,  he  has  probably  made  the  breach  in  the 
evidence  through  which  the  criminal  will  escape,  and  has  at  the  outset  de- 
feated the  aim  of  the  analysis. 

Analytical  Characters  of  the  Arsenical  Compounds. — ARSENOUS 
COMPOUNDS. — (1)  H2S,  a  yellow  color  in  neutral  or  alkaline  liquids; 
a  yellow  ppt.  in  acid  liquids.  The  ppt.  dissolves  in  solutions  of  the 
alkaline  hydroxides,  carbonates  and  sulphydrates ;  but  is  scarcely 
affected  by  HC1.  Hot  HN03  decomposes  it. 

(2)  AgN03,  in  the  presence  of  a  little  NH4OH,  gives  a  yellow 
ppt.  This  test  is  best  applied  by  placing  the  neutral  arsenical  solu- 
tion in  a  porcelain  capsule,  adding  neutral  solution  of  AgN03,  and 
blowing  upon  it  over  the  stopper  of  the  NH4OH  bottle,  moistened 
with  that  reagent. 


ARSENIC  117 

(3)  CuS04  under  the  same  conditions  as  in  (2)  gives  a  yellowish 
green  ppt. 

(4)  Reinsch  Test. — The  suspected  liquid  is  acidulated  with  one- 
sixth  its  bulk  of  HC1.     Strips  of  electrotype  copper  are  immersed  in 
the  liquid,  which  is  boiled.     In  the  presence  of  an  arsenous  com- 
pound, a  gray  or  bluish  deposit  is  formed  upon  the  Cu.     A  similar 
deposit  is  produced  by  other  substances  (S,  Au,  Pt,  Bi,  Sb,  Hg).    To 
complete  the  test  the  Cu  is  removed,  washed,  and  dried  between  folds 
of  filter  paper,  without  removing  the  deposit.     The  copper,  with  its 
adherent  film,  is  rolled  into  a  cylinder,  and  introduced  into  a  dry 
piece  of  Bohemian  tubing,  about  one-fourth  inch  in  diameter  and  six 
inches  long,  which  is  held  at  the  angle  shown  in  Fig.  13  and  heated 
at  the  point  containing  the  copper.    If  the  deposit  consists  of  arsenic, 
a  white  deposit  is  formed  at  a,  which  contains  brilliant  specks,  and, 
when  examined  with  a  magnifier,   is   found  to  consist  entirely   of 
minute  octahedral  crystals  (Fig.  14). 


FIG.  13.  FIG.   14. 

If  the  stain  upon  the  copper,  formed  in  the  first  part  of  the  reac- 
tion, has  been  caused  by  S,  Au,  Pt,  or  Bi,  no  sublimate  is  produced 
during  the  subsequent  heating  in  the  glass  tube,  as  the  product  of 
oxidation  of  sulphur  is  gaseous,  Au  and  Pt  are  neither  oxidized  nor 
volatilized,  and  Bi  is  oxidized,  but  its  oxide  is  not  volatile.  Subli- 
mates are,  however,  formed  from  deposits  caused  by  Sb  or  Hg,  which 
differ  from  that  produced  by  arsenic  in  the  following  respects :  That 
from  Sb  consists  of  Sb203,  which  is  entirely,  or  almost  entirely, 
amorphous,  or  granular,  possibly  containing  one  or  two  octahedral 
crystals,  whose  borders  are  darker  than  those  of  As203.  The  sub- 
limate from  Hg  consists  of  microscopic  globules  of  the  liquid  metal. 
Reinsch 's  reaction  is,  therefore,  a  test  for  antimony  and  mercury, 
as  well  as  for  arsenic. 

The  advantages  of  the  Reinsch  test  are :  it  may  be  applied  in  the 
presence  of  organic  matter,  to  the  urine  for  instance ;  it  is  easily  con- 
ducted; and  its  positive  results  are  not  misleading,  if  the  test  is 
carried  to  completion.  These  advantages  render  it  the  most  suitable 
method  for  the  physician  to  use,  during  the  life  of  the  patient.  It 


118 


TEXT-BOOK   OF    CHEMISTRY 


should  not  be  used  after  death  by  the  physician,  as  by  it  copper  is 
introduced  into  the  substances  under  examination,  which  may  sub- 
sequently interfere  seriously  with  the  analysis.  The  purity  of  the 
Cu  and  HC1  must  be  proved  by  a  blank  testing  before  use.  Reinsch's 
test  is  not  as  delicate  as  Marsh's,  and  it  only  reacts  slowly  and  im- 
perfectly when  the  arsenic  is  in  the  higher  stage  of  oxidation,  or  in 
presence  of  oxidizing  agents. 

(5)  Marsh's  test  is  based  upon  the  formation  of  AsH3  when  a 
reducible  compound  of  arsenic  is  in  presence  of  nascent  H ;  and  the 
subsequent  decomposition  of  the  arsenical  gas  by  heat,  with  separa- 
tion of  elementary  arsenic. 

The  apparatus  used  (Fig.  15)  consists  of  a  glass  generating  ves- 
sel, a,  of  about  150  cc.  capacity,  provided  with  a  funnel-tube  having 
a  stop-cock,  and  a  lateral  outlet,  either  fitted  in  with  a  cork,  or, 
better,  ground  in.  The  lateral  outlet  is  connected  with  a  tube,  6,  filled 
with  fragments  of  calcium  chloride ;  which  in  turn  connects  with  the 
Bohemian  glass  tube  cc,  which  should  be  about  0.5  cent,  in  diameter, 


FIG.  15. 


and  about  80  cent.  long.  The  tube  is  protected  by  a  tube  of  wire 
gauze,  within  which  it  is  adjusted  in  the  furnace  as  shown  in  the 
figure.  The  other  end  of  cc  is  bent  downward,  and  dips  into  a  solu- 
tion of  silver  nitrate  in  the  test-tube,  d. 

The  vessel  a  is  first  charged  with  about  25  grams  of  an  alloy 
of  pure  granulated  zinc,  with  a  small  quantity  of  platinum.  The 
apparatus  is  then  connected  gas-tight,  and  the  funnel  tube  about 
half  filled  with  H2S04,  diluted  with  an  equal  bulk  of  H20,  and  cooled. 
By  opening  the  stopcock,  the  acid  is  brought  in  contact  with  the  zinc 
in  small  quantities,  in  such  a  manner  that  during  the  entire  testing 
bubbles  of  gas  pass  through  d  at  the  rate  of  60-80  per  minute. 
After  fifteen  minutes  the  burner  is  lighted,  and  the  heating  continued, 
during  evolution  of  gas  from  zinc  and  H2S04,  for  an  hour.  At  the 
end  of  that  time,  if  no  stain  has  formed  in  cc  beyond  the  burner,  the 
zinc  and  acid  may  be  considered  to  be  pure,  and  the  suspected  solu- 


ARSENIC 


119 


tion,  which  must  have  been  previously  freed  from  organic  matter  and 
from  tin  and  antimony,  is  introduced  slowly  through  the  funnel-tube. 
If  arsenic  is  present  in  the  substance  examined,  a  hair-brown  or 
gray  deposit  is  formed  in  the  cool  part  of  cc  beyond  the  heated  part. 
At  the  same  time  the  contents  of  d  are  darkened  if  the  amount  of  As 
present  is  so  great  that  all  the  AsH3  produced  is  not  decomposed  in 
the  heated  portion  of  cc. 

To  distinguish  the  stains  produced  by  arsenical  compounds  from 
the  similar  ones  produced  by  antimony  the  following  differences  are 
noted  : 


The  Antimonial  Stain. 


The  Arsenical  Stain. 


1.  Is     farther     removed     from     the 
heated    portion    of    the    tube,    and,    if 
small  in  quantity,  is  double — the  first 
hair-brown,  the   second   steel-gray. 

2.  Volatilizes  readily  when  heated  in 
an  atmosphere  of  hydrogen,  being  de- 
posited farther  along  in  the  tube.    The 
escaping  gas  has  the  odor  of  garlic. 

3.  When  cautiously  heated  in  a  cur- 
rent of  oxygen,  brilliant,  white,  octahe- 
dral   crystals    of    arsenic    trioxide    are 
deposited  farther  along  in  the  tube. 

4.  Instantly    soluble    in   solution   of 
sodium  hypochlorite. 

5.  Slowly   dissolved    by    solution   of 
ammonium  sulphydrate;    more  rapidly 
when  warmed. 

6.  The     solution    obtained     in     (5) 
leaves,  on  evaporation  over  the  water- 
bath,  a  bright  yellow  residue. 

7.  The   residue    obtained    in    (6)    is 
soluble  in  aqua  ammonise,  but  insoluble 
in  hydrochloric  acid. 

8.  Is   soluble   in   warm   nitric   acid; 
the   solution    on   evaporation   yields   a 
white    residue,    which    turns    brick-red 
when    moistened    with    silver    nitrate 
solution. 

9.  Is  not  dissolved  by  a  solution  of 
stannous  chloride. 


1.  Is  quite  near  the  heated  portion 
of   the   tube.     A   second   stain   is   also 
usually  formed  in  front  of  the  heated 
part  of  the  tube. 

2.  Requires  a  much  higher  tempera- 
ture for  its  volatilization;  fuses  before 
volatilizing.       Escaping    gas     has     no 
alliaceous  odor. 

3.  No    crystals    formed    by    heating 
in    oxygen,    but    an    amorphous,    white 
sublimate   (see  p.  000). 

4.  Insoluble   in    solution   of   sodium 
hypochlorite. 

5.  Dissolves   quickly   in   solution   of 
ammonium  sulphydrate. 

6.  The     solution    obtained    in     (5) 
leaves,  on  evaporation  over  the  water- 
bath,  an  orange-red  residue. 

7.  The   residue    obtained    in    (6)    is 
insoluble  in  aqua  ammoniae,  but  soluble 
in  hydrochloric  acid. 

8.  Is   soluble   in   warm   nitric  acid; 
the    solution    on   evaporation   yields    a 
white    residue,    which    is    not    colored 
when    moistened    with    silver    nitrate 
solution. 

0.    Dissolves    slowly    in    solution    of 
stannous  chloride. 


The  silver  solution  in  d  is  tested  for  arsenous  acid,  by  floating 
upon  its  surface  a  layer  of  diluted  NH4OH  solution,  which,  in  the 
presence  of  arsenic,  produces  a  yellow  (not  brown)  band,  at  the  point 
of  junction  of  the  two  liquids. 

In  place  of  bending  the  tube  c  downward,  it  may  be  bent  upward 
and  drawn  out  to  a  fine  opening.  If  the  escaping  gas  is  then  ignited, 


120  TEXT-BOOK   OF   CHEMISTRY 

the  heating  of  the  tube  being  discontinued,  a  white  deposit  of  As203 
may  be  collected  on  a  glass  surface  held  above  the  flame ;  or  a  brown 
deposit  of  elementary  As  upon  a  cold  (porcelain)  surface  heir1  in  the 
flame. 

In  place  of  generating  nascent  hydrogen  by  the  action  of  Zn  on 
H2S04,  it  may  be  produced  by  the  decomposition  of  acidulated  H20 
by  the  battery,  in  a  Marsh  apparatus  especially  modified  for  that 
purpose. 

In  another  modification  of  the  Marsh  test  the  AsH3  is  decomposed, 
not  by  passage  through  a  red-hot  tube,  but  by  passing  through  a 
tube  traversed  by  the  spark  from  an  induction  coil. 

ARSENIC  COMPOUNDS. — (1)  H2S  does  not  form  a  ppt.  in  neutral 
or  alkaline  solutions.  In  acid  solutions  a  yellow  ppt.,  consisting 
either  of  As2S3  or  As2S.,,  or  a  mixture  of  the  sulphides  with  free  S,  is 
formed  only  after  prolonged  passage  of  H2S  at  the  ordinary  tempera- 
ture, more  rapidly  at  about  70  °. 

(2)  AgN03,  under  the  same  conditions  as  with  the  arsenous  com- 
pounds, produces  a  brick-red  ppt.  of  silver  arsenate. 

(3)  CuS04  under  like  circumstances  produces  a  bluish  green  ppt. 
Arsenic  compounds  behave  like  arsenous  compounds  with  Marsh's 

test. 

ANTIMONY. 

Symbol=$\)  (Latin:  stibium) — Atomic  weight=12Q  (Inter- 
national—120.2) — Molecular  weight— ( ?) — Sp.  #r.=6.175. 

Occurrence. — Free  in  small  quantity;  principally  in  the  trisul- 
phide,  Sb,S3. 

Preparation. — The  native  sulphide  (black  or  crude  antimony)  is 
roasted,  and  then  reduced  by  heating  with  charcoal. 

Properties. — Physical. — A  bluish  gray,  brittle  solid,  having  a 
metallic  luster;  readily  crystallizable ;  tasteless  and  odorless;  vola- 
tilizes at  a  red  heat,  and  may  be  distilled  in  an  atmosphere  of  H. 

Chemical. — Is  not  altered  by  dry  or  moist  air  at  ordinary  tempera- 
tures. When  sufficiently  heated  in  air,  it  burns,  with  formation  of 
Sb203,  as  a  white,  crystalline  solid.  It  also  combines  directly  with 
Cl,  Br,  I,  S,  and  many  metallic  elements.  It  combines  with  H  under 
the  same  circumstances  as  does  As.  Cold  dilute  H2S04  does  not  affect 
it;  the  hot  concentrated  acid  forms  with  it  antimonyl  sulphate 
(SbO)2S04  and  S02.  Hot  HC1  dissolves  it,  when  finely  divided,  with 
evolution  of  H.  It  is  readily  oxidized  by  HNO.{.  with  formation  of 
H3Sb04  or  Sb,04.  Aqua  regia  dissolves  it  as  SbCl3,  or  SbCl5.  Solu- 
tions of  the  alkaline  hydroxides  do  not  act  on  it. 

The  element  does  not  form  salts  with  the  oxyacids.  There  are,  how- 
ever, compounds,  formed  by  the  substitution  of  the  group  antimonyl 
(SbO),  for  the  basic  hydrogen  of  those  acids.  (Sec  Tartar  emetic.) 


ANTIMONY  121 

It  enters  into  the  composition  of  type  metal,  anti-friction  metals, 
and  britannia  metal. 

Hydrogen  Antimonide — Stibine — Antimoniuretted  hydrogen — 
SbH3 — 123. — It  is  produced,  mixed  with  H,  when  a  reducible  com- 
pound of  Sb  is  in  presence  of  nascent  H.  It  is  obtained  in  larger 
amount  by  decomposing  an  alloy  of  400  parts  of  a  2%  sodium 
amalgam,  and  8  parts  of  freshly  reduced,  and  dried  Sb,  by  H20,  in 
a  current  of  C02. 

It  is  a  colorless,  odorless,  combustible  gas,  subject  to  the  same 
decompositions  as  AsH3 ;  from  which  it  differs  in  being  by  no  means 
as  poisonous,  and  in  its  action  upon  silver  nitrate  solution.  The 
arsenical  gas  acts  upon  the  silver  salt  according  to  the  equation  : 

6AgN03+2AsH3+H2=Ag2+2Ag2HAs03+6HN02 

and  the  precipitate  formed  is  elementary  silver,  while  Ag2HAs03 
remains  in  the  solution.    In  the  case  of  SbH3  the  reaction  is 

3AgN03+SbH3=3HN03+SbAg3, 
all  of  the  Sb  being  precipitated  in  the  black  silver  antimonide. 

Chlorides  of  Antimony. — Antimony  Trichloride — Butter  of  antimony — 
SbCl3 — 226.5 — is  obtained  by  passing  dry  Cl  over  an  excess  of  Sb2S3;  by  dis- 
solving Sb2S3  in  HC1 : 

Sb2S3-f6HCl=3H2S+2SbCls 

Or  by  distilling  mixtures,  either  of  Sb2S3  and  mercuric  chloride,  or  of  Sb  and 
mercuric  chloride. 

At  low  temperatures  it  is  a  solid,  crystalline  body;  at  the  ordinary  tem- 
perature a  yellow,  semi-solid  mass,  resembling  butter;  at  73.2°,  it  fuses  to  a 
yellow,  oily  liquid,  which  boils  at  223°. 

It  absorbs  moisture  from  air,  and  is  soluble  in  a  small  quantity  of  H2O; 
with  a  larger  quantity  it  is  decomposed,  with  precipitation  of  a  white  powder, 
powder  of  Algaroth,  whose  composition  is  SbOCl  if  cold  H2O  be  used,  and 
Sb405Cl2  if  the  H2O  be  boiling.  In  H20  containing  15  per  cent,  or  more  HC1, 
SbCl3  is  soluble  without  decomposition. 

Antimony  Pentachloride— SbCl5— 297.5 — is  formed  by  the  action  of  Cl 
in  excess,  upon  Sb  or  SbCl3: 

SbCl3+Cl2=SbCl5 

It  is  a  fuming,  colorless  liquid.  With  a  small  quantity  of  H20,  and 
evaporation  over  H2S04,  it  forms  a  hydrate,  SbCl54H2O,  which  appears  in  trans- 
parent, deliquescent  crystals.  With  more  H20,  a  crystalline  oxychloride,  SbOCl3, 
is  formed;  and  with  still  greater  quantity,  a  white  precipitate  of  orthoantimonic 
acid,  H3Sb04. 

Compounds  of  Antimony  and  Oxygen.— Three  are  known,  Sb203, 
Sb204  and  Sb205. 

Antimony  Trioxide— Antimonous  anhydride — Oxide  of  antimony 
— Sb203 — 288 — occurs  in  nature ;  and  is  prepared  artificially  by  heat- 
ing Sb  in  air,  or  by  decomposing  the  oxychloride : 

2SbOCl+Na2C03=2NaCl-(-C02+Sb203 


122  TEXT-BOOK   OF   CHEMISTRY 

It  crystallizes  in  prisms  or  in  octahedra,  and  is  isodimorphous 
with  As203,  or  is  an  amorphous,  insoluble,  tasteless,  odorless  powder ; 
white  at  ordinary  temperatures,  but  yellow  when  heated.  It  fuses 
readily,  and  may  be  distilled  in  absence  of  oxygen.  Heated  in  air,  it 
burns  like  tinder,  and  is  converted  into  Sb204. 

It  is  reduced,  with  separation  of  Sb,  when  heated  with  charcoal, 
or  in  H.  It  is  already  oxidized  by  HN03,  or  potassium  perman- 
ganate. It  dissolves  in  HC1  as  SbCl3 ;  in  Nordhausen  sulphuric  acid, 
from  which  solution  brilliant  crystalline  plates  of  antimonyl  pyrosul- 
phate,  (SbO)2S207,  separate;  and  in  solutions  of  tartaric  acid,  and  of 
hydropotassic  tartrate  (see  Tartar  emetic).  Boiling  solutions  of  alka- 
line hydroxides  convert  it  into  antirnonic  acid. 

Antimony  Pentoxide — Antimonic  anhydride — Sb205 — 320— is  ob- 
tained by  heating  metantimonic  acid  to  dull  redness.  It  is  an  amor- 
phous, tasteless,  odorless,  pale  lemon-yellow  colored  solid;  very  spar- 
ingly soluble  in  water  and  in  acids.  At  a  red  heat  it  is  decomposed 
into  Sb204  and  0. 

Antimony  Acids. — The  normal  antimonous  acid,  H3SbO3,  corresponding  to 
H3PO3,  is  unknown;  but  the  series  of  antimonic  acids:  ortho,  H3SbO4;  pyro, 
H4Sb2OT;  and  meta,  HSbO3,  is  complete,  either  in  the  form  of  salts,  or  in  that 
of  the  free  acids.  There  also  exists,  in  its  sodium  salt,  a  derivative  of  the 
lacking  antimonous  acid:  metantimonous  acid,  HSb02. 

Sulphides  of  Antimony. — Antimony  Trisulphide — Black  anti- 
mony— Sb2S3 — 336 — is  the  chief  ore  of  antimony;  and  is  formed 
when  H2S  is  passed  through  a  solution  of  tartar  emetic. 

The  native  sulphide  is  a  steel-gray,  crystalline  solid ;  the  artificial 
product,  an  orange-red,  or  brownish-red,  amorphous  powder.  The 
crude  antimony  of  commerce  is  in  conical  loaves,  prepared  by  simple 
fusion  of  the  native  sulphide.  It  is  soft,  fusible,  readily  pulverized, 
and  has  a  bright  metallic  luster. 

Heated  in  air,  it  is  decomposed  into  S02  and  a  brown,  vitreous, 
more  or  less  transparent  mass,  composed  of  varying  proportions  of 
oxide  and  oxysulphides,  known  as  crocus,  or  liver,  or  glass  of  anti- 
mony. Sb.,S3  is  an  anhydride,  corresponding  to  which  are  salts  known 
as  thioantimonites,  having  the  general  formula  M'2HSbS3.  If  an 
excess  of  Sb2S3  is  boiled  with  a  solution  of  potash  or  soda,  a  liquid  is 
obtained,  which  contains  an  alkaline  thioantimonite,  and  an  excess 
of  Sb2S3.  If  this  solution  is  filtered  and  allowed  to  cool,  a  brown, 
voluminous,  amorphous  precipitate  separates,  which  consists  of  anti- 
mony trisulphide  and  trioxide,  potassium  or  sodium  sulphide,  and 
alkaline  thioantimonite  in  varying  proportions;  and  is  known  as 
Kermes  mineral. 

Antimony  Pentasulphide — Sb,S5 — 400 — is  obtained  by  decom- 
posing an  alkaline  thioantimonate  by  an  acid.  It  is  a  dark  orange- 
red,  amorphous  powder,  readily  soluble  in  solutions  of  the  alkalies, 
and  alkaline  sulphides,  with  which  it  forms  thioantimonates. 


BORON  123 

Action  of  Antimony  Compounds  on  the  Economy. — The  compounds  of 
antimony  are  poisonous,  and  act  with  greater  or  less  energy  as  they  are  more 
or  less  soluble.  The  compound  which  is  most  frequently  the  cause  of  antimonial 
poisoning  is  tartar  emetic  (q.  v.) ,  which  has  caused  death  in  a  quantity  of  three 
grains,  in  divided  doses,  although  recovery  has  followed  the  ingestion  of  half  an 
ounce  in  several  instances.  Indeed,  the  chances  of  recovery  seem  to  be  better 
with  large,  than  with  small  doses,  probably  owing  to  the  more  rapid  and  com- 
plete removal  of  the  poison  by  vomiting  with  large  doses.  Antimonials  have 
been  sometimes  criminally  administered  in  small  and  repeated  doses,  the  victim 
dying  of  exhaustion.  In  such  a  case  an  examination  of  the  urine  will  reveal 
the  cause  of  the  trouble. 

If  vomiting  has  not  occurred  in  cases  of  acute  antimonial  poisoning  it 
should  be  provoked  by  apomorphine  or  warm  water,  or  the  stomach  should  be 
washed  out.  Tannin  in  some  form  (decoction  of  oak  bark,  cinchona,  nutgalls, 
tea)  should  then  be  given,  with  a  view  to  rendering  any  remaining  poison 
insoluble. 

Medicinal  antimonials  are  very  liable  to  contamination  with  arsenic. 

Analytical  Characters  of  Antimonial  Compounds. —  (1)  With 
HoS  in  acid  solution:  an  orange-red  ppt.,  soluble  in  NH4HS  and  in 
hot  HC1. 

(2)  A  strip  of  bright  copper,  suspended  in  a  boiling  solution  of 
an  Sb  compound,  acidulated  with  HC1,  is  coated  with  a  blue-gray 
deposit.     This  deposit  when  dried  (on  the  copper),  and  heated  in  a 
tube  open  at  both  ends  yields  a  white,  amorphous  sublimate   (see 
Reinsch's  test,  p.  117). 

(3)  Antimonial  compounds  yield  a  deposit  by  Marsh's  test,  sim- 
ilar to  that  obtained  with  arsenical  compounds,  but  differing  in  the 
particulars  given  above  (see  Marsh's  test,  pp.  118,  119). 


IV.    BORON  GROUP. 
BORON. 

=B — Atomic   weight =11.    (International^ll.Q) — Molecu- 
lar weight=22. 

Boron  occurs  in  nature  in  the  borates  of  Ca,  Mg,  and  Na,  princi- 
pally as  sodium  pyroborate  (borax).  It  constitutes  a  group  by  itself; 
it  is  trivalent  in  all  its  compounds;  it  forms  but  one  oxide,  which 
is  the  anhydride  of  a  tribasic  acid ;  and  it  forms  no  compound 
with  H. 

It  is  separable  in  two  allotropic  modifications.  Amorphous 
boron  is  prepared  by  decomposition  of  the  oxide,  by  heating  with 
metallic  potassium  or  sodium: 

B203+3Na2=3Na20+B2 

It  is  a  greenish  brown  powder;  sparingly  soluble  in  H20;  in- 
fusible; and  capable  of  direct  union  with  Cl,  Br,  0,  S,  and  N. 


124  TEXT-BOOK   OF   CHEMISTRY 

Crystallized  boron  is  produced  when  the  oxide,  chloride  or  fluoride 
is  reduced  by  Al.  It  crystallizes  in  quadratic  prisms;  more  or  less 
transparent,  and  varying  in  color  from  a  faint  yellow  to  deep  garnet- 
red  ;  very  hard ;  sp.  gr.  2.68.  It  burns  when  strongly  heated  in  0,  and 
readily  in  Cl;  it  also  combines  with  N,  which  it  is  capable  of  re- 
moving from  NH3  at  a  high  temperature. 

Boron  Trioxide. — Boric  or  boracic  anhydride — B.,03 — 70 — is  ob- 
tained by  heating  boric  acid  to  redness  in  a  platinum  vessel.  It  is  a 
transparent,  glass-like  mass,  used  in  blowpipe  analysis  under  the 
name  vitreous  boric  acid. 

Boric     Acids. — Boric     Acid — Boracic     acid — Orthoboric     acid — 

Acidum  boricum  (U.  S.  P.) — H3B03 — 62 — occurs  in  nature;  and  is 

prepared  by  slowly  decomposing  a  boiling,  concentrated  solution  of 

borax,  with  an  excess  of  H2S04,  and  allowing  the  acid  to  crystallize : 

Na2B407+H2S04+5H20=Na2S04+4H3B03 

It  forms  brilliant,  crystalline  plates,  unctuous  to  the  touch ;  odor- 
less ;  slightly  bitter ;  soluble  in  34  parts  H20  at  10° ;  soluble  in  alcohol. 
Its  solution  reddens  litmus,  but  turns  turmeric  paper  brown.  When 
its  aqueous  solution  is  distilled,  a  portion  of  the  acid  passes  over. 

Boric  acid  readily  forms  esters  with  the  alcohols.  When  heated 
with  ethylic  alcohol,  ethyl  borate  is  formed,  which  burns  with  a 
green  flame.  Heated  with  glycerol,  a  soluble,  neutral  ester  is  formed, 
known  as  boroglyceride,  and  used  as  an  antiseptic. 

If  H3B03  be  heated  for  some  time  at  80°,  it  loses  H20  and  is 
converted  into  metaboric  acid,  HB02.  If  maintained  at  100°  for 
several  days,  it  loses  a  further  quantity  of  H20,  and  is  converted 
into  tetraboric  or  pyroboric  acid,  H2B407,  whose  sodium  salt  is 
borax.  (See  p.  154.) 


V.     CARBON  GROUP. 
CARBON— SILICON. 

The  elements  of  this  group  are  quadrivalent.  The  saturated 
oxide  of  each  is  the  anhydride  of  a  dibasic  acid.  They  are  both 
combustible,  and  each  occurs  in  three  allotropic  forms. 

CARBON. 

Symbolic — Atomic  weight=l2  (International— 12.005) — Molec- 
ular weight=24:. 

Occurrence. — Free  in  its  three  allotropic  forms:  The  diamond 
in  octahedral  crystals;  in  alluvial  sand,  clay,  sandstone,  and  con- 
glomerate; graphite,  in  amorphous  or  imperfectly  crystalline  forms; 
amorphous,  in  the  different  varieties  of  anthracite  and  bituminous 


CARBON  125 

coal,  jet,  etc.  In  combination,  it  is  very  widely  distributed  in  the 
so-called  organic  substances. 

Properties. — Diamond. — The  crystals  of  diamond,  which  is  al- 
most pure  carbon,  are  usually  colorless  or  yellowish,  but  may  be  blue, 
green,  pink,  brown  or  black.  It  is  the  hardest  substance  known, 
and  the  one  which  refracts  light  the  most  strongly.  Its  index  of 
refraction  is  2.47  to  2.75.  It  is  brittle ;  a  bad  conductor  of  heat  and 
of  electricity;  sp.  gr.  3.50  to  3.55.  When  very  strongly  heated  in  air 
it  burns,  without  blackening,  to  carbon  dioxide. 

Graphite  is  a  form  of  carbon  almost  as  pure  as  the  diamond, 
capable  of  crystallizing  in  hexagonal  plates ;  sp.  gr.  2.2 ;  dark  gray  in 
color;  opaque;  soft  enough  to  be  scratched  by  the  nail;  and  a  good 
conductor  of  electricity.  It  is  also  known  as  black  lead  or  plum- 
bago. It  has  been  obtained  artificially,  by  allowing  molten  cast-iron, 
containing  an  excess  of  carbon,  to  cool  slowly,  and  dissolving  the 
iron  in  HC1.  When  oxidized  with  potassium  chlorate  and  nitric  acid 
it  yields  graphitic  acid,  CnH405. 

Amorphous  carbon  is  met  with  in  a  great  variety  of  forms,  nat- 
ural and  artificial,  in  all  of  which  it  is  black;  sp.  gr.  1.6-2.0;  more 
or  less  porous ;  and  a  conductor  of  electricity. 

Anthracite  coal  is  hard  and  dense;  it  does  not  flame  when  burn- 
ing; is  difficult  to  kindle,  but  gives  great  heat  with  a  suitable 
draught.  It  contains  80-90  per  cent,  of  carbon.  Bituminous  coal 
differs  from  anthracite  in  that,  when  burning,  it  gives  off  gases, 
which  produce  a  flame.  Some  varieties  are  quite  soft,  while  others, 
such  as  jet,  are  hard  enough  to  assume  a  high  polish.  It  is  usually 
compact  in  texture,  and  very  frequently  contains  impressions  of 
leaves,  ^and  other  parts  of  plants.  It  contains  about  75  per  cent,  of 
carbon. 

Charcoal,  wood  charcoal,  carbo  ligni,  (U.  S.  P.)  is  obtained  by 
burning  woody  fiber,  with  an  insufficient  supply  of  air.  It  is  brittle 
and  sonorous ;  has  the  form  of  the  wood  from  which  it  was  obtained, 
and  retains  all  the  mineral  matter  present  in  the  woody  tissue.  Its 
sp.  gr.  is  about  1.57.  It  has  the  power  of  condensing  within  its  pores 
odorous  substances  and  large  quantities  of  gases;  90  volumes  of 
ammonia,  55  of  hydrogen  sulphide,  9.25  of  oxygen.  This  property 
is  taken  advantage  of  in  a  variety  of  ways.  Its  power  of  absorbing 
odorous  bodies  renders  it  valuable  as  a  disinfecting  and  filtering 
agent,  and  in  the  prevention  of  putrefaction  and  fermentation  of 
certain  liquids.  The  efficacy  of  charcoal  as  a  filtering  material  is 
due  also,  in  a  great  measure,  to  the  oxidizing  action  of  the  oxygen 
condensed  in  its  pores ;  indeed,  if  charcoal  is  boiled  with  dilute  HC1, 
dried,  and  heated  to  redness,  the  oxidizing  action  of  the  oxygen,  which 
it  thus  condenses,  is  very  energetic. 

When  small  strips  of  wood  are  heated  to  redness  in  a  current  of 
vapor  of  carbon  disulphide,  or  of  hydrocarbons,  metallic  carbon  is 


126  TEXT-BOOK   OF   CHEMISTRY 

produced.  This  is  very  sonorous,  and  is  a  very  good  conductor  of 
heat  and  of  electricity.  The  filaments  in  incandescent  electric  lamps 
are  prepared  from  vegetable  parchment  or  bamboo  fiber  in  a  similar 
manner. 

Lamp-black  is  obtained  by  incomplete  combustion  of  some  resi- 
nous or  tarry  substance,  or  natural  gas,  the  smoke  or  soot  from  which 
is  directed  into  suitable  condensing  chambers.  It  is  a  light  amor- 
phous powder,  and  contains  a  notable  quantity  of  oily  and  tarry 
material,  from  which  it  may  be  freed  by  heating  in  a  covered  vessel. 
It  is  used  in  the  manufacture  of  printer's  ink. 

Coke  is  the  substance  remaining  in  gas  retorts,  after  the  distil- 
lation of  bituminous  coal,  in  the  manufacture  of  illuminating  gas. 
It  is  a  hard,  grayish  substance,  usually  very  porous,  dense,  and 
sonorous.  When  iron  retorts  are  used,  a  portion  of  the  gaseous 
products  are  decomposed  by  contact  with  the  hot  iron  surface,  upon 
which  there  is  then  deposited  a  layer  of  very  hard,  compact,  grayish 
carbon,  which  is  a  good  conductor  of  electricity. 

Animal  charcoal  is  obtained  by  calcining  animal  matters  in  closed 
vessels.  If  prepared  from  bones  it  is  known  as  bone-black,  carbo 
animalis;  if  from  ivory,  ivory  black.  The  latter  is  used  as  a  pig- 
ment, the  former  as  a  decolorizing  agent.  Bones  yield  about  60  per 
cent,  of  bone-black,  which  contains,  besides  carbon,  nitrogen  and 
the  phosphates  and  other  mineral  substances  of  the  bones.  It  pos- 
sesses in  a  remarkable  degree  the  power  of  absorbing  coloring  mat- 
ters. When  its  decolorizing  power  is  lost  by  saturation  with  pig- 
mentary bodies,  it  may  be  restored,  although  not  completely,  by  cal- 
cination. For  certain  purposes  purified  animal  charcoal,  i.e.,  freed 
from  mineral  matter,  carbo  animalis  purificatus,  is  required,  and  is 
obtained  by  extracting  the  commercial  article  with  HC1,  and  wash- 
ing it  thoroughly.  Its  decolorizing  power  is  diminished  by  this 
treatment.  Animal  charcoal  has  the  power  of  removing  from  a  solu- 
tion certain  crystalline  substances,  notably  the  alkaloids,  and  a 
method  has  been  suggested  for  separating  these  bodies  from  organic 
mixtures  by  its  use. 

All  forms  of  carbon  are  insoluble  in  any  known  liquid. 

Chemical. — All  forms  of  C  combine  with  0  at  high  temperatures, 
with  light  and  heat.  The  product  of  the  union  is  carbon  dioxide  if 
the  supply  of  air  or  0  is  sufficient ;  but  if  0  is  present  in  limited  quan- 
tity, carbon  monoxide  is  formed.  The  affinity  of  C  for  0  renders  it  a 
valuable  reducing  agent.  Many  metallic  oxides  are  reduced,  when 
heated  with  C,  and  steam  is  decomposed  when  passed  over  red-hot  C : 
H20-f  C=CO-j-H2.  At  elevated  temperatures  C  also  combines  di- 
rectly with  S,  to  form  carbon  disulphide.  With  H,  carbon  also  com- 
bines directly,  under  the  influence  of  the  voltaic  arc. 

For  Compounds  of  Carbon,  see  page  191. 


SILICON  127 


SILICON. 

Symbol— ^>\— Atomic  weight=2S  (International,  28.3) — Molecu- 
lar weight=56. 

Also  known  as  silicium;  occurs  in  three  allotropic  forms:  Amor- 
phous silicon,  formed  when  silicon  chloride  is  passed  over  heated  K 
or  Na,  is  a  dark  brown  powder,  heavier  than  water.  When  heated  in 
air,  it  burns  with  a  bright  flame  to  the  dioxide.  It  dissolves  in  potash 
and  in  hydrofluoric  acid,  but  is  not  attacked  by  other  acids.  Graphi- 
toid  silicon  is  obtained  by  fusing  potassium  fluosilicate  with  alumin- 
ium. It  forms  hexagonal  plates,  of  sp.  gr.  2.49,  which  do  not  burn 
when  heated  to  whiteness  in  0,  but  may  be  oxidized  at  that  tem- 
perature, by  a  mixture  of  potassium  chlorate  and  nitrate.  It  dis- 
solves slowly  in  alkaline  solutions,  but  not  in  acids.  Crystallized 
silicon,  corresponding  to  the  diamond,  forms  crystalline  needles, 
which  are  only  attacked  by  a  mixture  of  nitric  and  hydrofluoric 
acids. 

Silicon,  although  closely  related  to  C,  exists  in  nature  in  compara- 
tively few  compounds ;  it  occurs  abundantly,  however,  as  silicon 
dioxide  and  in  the  form  of  silicates. 

Silicon  Chloride — SiCl4 — 170 — a  colorless,  volatile  liquid,  having  an  irritat- 
ing odor;  sp.  gr.  1.52;  boils  at  59°;  formed  when  Si  is  heated  to  redness  in  Cl. 

Silicon  Dioxide — Silica — Silicic  Oxide — Silicic  anhydride — Silex — Si02 — 
60 — is  the  most  important  of  the  compounds  of  silicon.  It  exists  in  nature  in 
the  different  varieties  of  quartz,  and  in  the  rocks  and  sands  containing  that 
mineral,  in  agate,  carnelian,  flint,  etc.  Its  purest  native  form  is  rock  crystal. 
It  may  be  obtained  by  heating  a  solution  of  sodium  silicate  with  hydrochloric 
acid:  Na2Si03-f 2HCl=2NaCl-|-H2O-f-SiO2.  Its  hydrates  occur  in  the  opal,  and 
in  solution  in  natural  waters. 

When  crystallized,  it  is  fusible  with  difficulty.  When  heated  to  redness 
with  the  alkaline  carbonates,  it  forms  silicates,  which  solidify  to  glass-like 
masses,  on  cooling.  It  unites  with  H2O  to  form  a  number  of  acid  hydrates.  The 
normal  hydrate,  H4SiO4,  has  not  been  isolated,  although  it  probably  exists  in  the 
solution  obtained  by  adding  an  excess  of  HC1  to  a  solution  of  sodium  silicate.  A 
gelatinous  hydrate,  soluble  in  water  and  in  acids  and  alkalies,  is  obtained  by 
adding  a  small  quantity  of  HC1  to  a  concentrated  solution  of  sodium  silicate. 

Hydrofluosilicic  Acid — H,SiF6 — 144 — is  obtained  in  solution  by  passing  the 
gas  disengaged  by  gently  heating  a  mixture  of  equal  parts  of  fluorspar  and 
pounded  glass  and  6  pts.  H2S04  through  water;  the  disengagement  tube  being 
protected  from  moisture  by  a  layer  of  mercury.  It  is  used  in  analysis  as  a 
test  for  K  and  Na. 

Silicon  Carbide — SiC — is  produced  by  the  action  of  a  powerful  electric 
current  upon  a  mixture  of  coke  and  aluminium  silicate.  It  forms  blue  crystals, 
is  very  hard,  and  is  used  as  a  polishing  agent  under  the  name  Carborundum. 


128  TEXT-BOOK   OF   CHEMISTRY 

VI.     VANADIUM  GROUP. 
VANADIUM— COLUMBIUM— TANTALUM. 

The  elements  of  this  group  resemble  those  of  the  N  group,  but 
are  usually  quadrivalent. 

Vanadium — V — 51  (International=51.0) — a  brilliant,  crystalline 
metal;  sp.  gr.=5.5;  which  forms  a  series  of  oxides  similar  to  those 
of  N.  No  salts  of  V  are  known,  but  salts  of  vanadyl  (VO)  are 
numerous,  and  are  used  in  the  manufacture  of  aniline  black. 

Columbium  (Niobium) — Cb.  93 — (International=93.1 — a  bright, 
steel-gray  metal;  sp.  gr.  7.06;  which  burns  in  air  to  Cb203  and  in 
Cl  to  CbCl5 ;  not  attacked  by  acids. 

Tantalum — Ta — 181—  ( International=181.5 )  — closely  resembles 
Cb  in  its  chemical  characters. 

VII.    MOLYBDENUM  GROUP. 
MOLYBDENUM— TUNGSTEN— OSMIUM. 

The  position  of  this  group  is  doubtful ;  and  it  is  probable  that  the 
lower  oxides  will  be  found  to  be  basic  in  character,  in  which  case  the 
group  should  be  transferred  to  the  third  class. 

Molybdenum — Mo — 96 — a  brittle  white  metal.  The  oxide  Mo03, 
molybdic  anhydride,  combines  with  H20  to  form  a  number  of  acids; 
the  ammonium  salt  of  one  of  which  is  used  as  a  reagent  for  H3P04, 
with  which  it  forms  a  conjugate  acid,  phosphomolybdic  acid,  used  as  a 
reagent  for  the  alkaloids. 

Tungsten — Wolframium — W — 184 — a  hard,  brittle  metal;  sp.  gr. 
17.4.  The  oxide,  W03  tungstic  anhydride,  is  a  yellow  powder,  form- 
ing with  H20  several  acid  hydrates ;  one  of  which,  metatungstic  acid, 
is  used  as  a  test  for  the  alkaloids,  as  are  also  the  conjugate  silico- 
tungstic  and  phosphotungstic  acids.  Tissues  impregnated  with  sodium 
tungstate  are  rendered  uninflammable. 

Osmium — Os — 191 — (International=190.9) — occurs  in  combina- 
tion with  Ir  in  Pt  ores;  combustible  and  readily  oxidized  to  Os04. 
This  oxide,  known  as  osmic  acid,  forms  colorless  crystals,  soluble  in 
H20,  which  gives  off  intensely  irritating  vapors.  It  is  used  as  a 
staining  agent  by  histologists,  and  also  in  dental  practice. 


CLASS  IV.— AMPHOTERIC  ELEMENTS. 

Elements  whose  Oxides  unite  with  Water,  some  to  form  Bases,  others  to 
form  Acids;  which  form  Oxysalts. 

The  elements  of  this  class  are  intermediate  between  the  acidulous 
and  the  basylous  elements,  not  only  in  the  chemical  relations  of  their 
oxides,  but  also  in  the  products  of  their  electrolytic  dissociation. 
While  the  acidulous  elements  usually  exist  in  ionized  solutions  in 
anions,  which  may  be  simple  or  compound,  and  the  basylous  elements 
exist  only  in  cations,  which  are  always  simple,  the  amphoteric  elements 
may  exist  in  either  anion  or  cation.  When  they  occur  in  cations  the 
ions  are  almost  always  simple,  as  triaurion,  Au ' ' ' ,  dif errion,  Fe ' ' , 
plumbion,  Pb"  etc.,  although  rarely  they  are  compound,  as  diurany- 
lion,  U02".  When  they  occur  in  anions  these  are  invariably  com- 
pounds, as  dichromanion,  Cr207",  permanganion,  Mn04",  ferrocya- 
nidion,  Fe(CN)6"",  etc. 


I.     GOLD  GROUP. 
GOLD. 

Symbol=Au  (Aurum) — Atomic  weight=197 — (International^ 
197.2)— Molecular  weight=394:.  Sp.  gr.=l9.25S— 19.367. 

Gold  forms  two  series  of  compounds ;  in  one,  AuCl,  it  is  univalent ; 
in  the  other,  AuCl3,  trivalent.  Its  hydroxide,  auric  acid,  Au  (OH)3, 
corresponds  to  the  oxide,  Au203.  Its  oxysalts  are  unstable. 

It  is  yellow  or  red  by  reflected  light,  green  by  transmitted  light, 
reddish  purple  when  finely  divided;  not  very  tenacious;  softer  than 
silver;  very  malleable  and  ductile.  It  is  not  acted  on  by  H20  or  air, 
at  any  temperature,  nor  by  any  single  acid.  It  combines  directly  with 
Cl,  Br,  I,  P,  Sb,  As  and  Hg.  It  dissolves  in  nitrohydrochloric  acid. 

Aurous  Chloride — AuCl — is  produced  when  auric  chloride  is 
heated  to  185°  (365°  F.). 

Auric  Chloride— Gold  trichloride— AuC\3— 303.5— obtained  by 
dissolving  Au  in  aqua  regia,  evaporating  at  100°,  and  purifying  by 
crystallization  from  H20.  Deliquescent,  yellow  prisms,  very  soluble 
in  H20,  alcohol  and  ether;  readily  decomposed,  with  separation  of 
Au,  by  contact  with  P,  or  with  reducing  agents.  Its  solution,  treated 
with  the  chlorides  of  tin,  deposits  a  purple  double  stannate  of  Sn  and 
Au,  called  "purple  of  Cassius."  With  alkaline  chlorides  it  forms 

129 


130  TEXT-BOOK    OF    CHEMISTRY 

double  chlorides,  such  as  auri  et  sodii  chloridum  (U.  S.  P.),  which 
is  a  mixture  of  equal  parts  of  gold  chloride  and  sodium  chloride. 

Analytical  Characters. —  (1)  With  H2S,  from  neutral  or  acid  solu- 
tion :  a  blackish  brown  ppt.  in  the  cold ;  insoluble  in  HN03  and  in 
HC1;  soluble  in  aqua  regia,  and  in  yellow  NH4HS.  (2)  With  stan- 
nous  chloride  and  a  little  chlorine  water,  a  purple-red  ppt.,  insoluble 
in  HC1.  (3)  With  ferrous  sulphate:  a  brown  deposit,  which  assumes 
the  luster  of  gold  when  dried  and  burnished. 

II.    IRON  GROUP. 

CHROMIUM— MANGANESE— IRON. 

The  elements  of  the  group  form  two  series  of  compounds.  In  one 
they  are  bivalent,  as  in  FeCU  or  MnS04,  forming  the  -ous  salts; 
while  in  the  other  they  are  trivalent,  as  in  FeCl3,  forming  the  -ic 
salts.  They  form  several  oxides;  of  which  the  oxide  M03  is  an 
anhydride,  corresponding  to  which  are  acids  and  salts.  Most  of  the 
other  oxides  are  basic. 

CHROMIUM. 

Symbol=Cr — Atomic  weight=52 — (International=52,.Q) — Molec- 
ular weight=l04:.  Sp.  #r.=6.8. 

Occurs  in  nature  principally  as  chrome  ironstone,  a  double  oxide 
of  Cr  and  Fe.  The  element  is  separated  with  difficulty  by  reduction 
of  its  oxide  by  charcoal,  or  of  its  chloride  by  sodium.  It  is  a  hard, 
crystalline,  almost  infusible  metal.  Combines  with  O  only  at  a  red 
heat.  It  is  not  attacked  by  acids,  except  HC1 ;  is  readily  attacked  by 
alkalies. 

Chromic   Oxide — Chromium   Sesquioxide — Cr203 — 152 — obtained 
by  heating  potassium  dichromate  with  sulphur: 
K2Cr207+S=K2S04+Cr203 

It  is  green;  insoluble  in  H20,  acids  and  alkalies;  fusible  with 
difficulty,  and  not  decomposed  by  heat ;  not  reduced  by  H.  At  a  red 
heat  in  air,  it  combines  with  alkaline  hydroxides  and  nitrates,  to 
form  chromates.  It  forms  two  series  of  salts,  the  terms  of  one  of 
which  are  green,  those  of  the  other  violet.  The  alkaline  hydroxides 
separate  a  bluish-green  hydrate  from  solutions  of  the  green  salts,  and 
a  bluish  violet  hydrate  from  those  of  the  violet  salts. 

Chromium  Trioxide — Chromic  anhydride — Chromium  Tri- 
oxidum  (U.  S.  P.) — Cr03 — 100 — is  formed  by  decomposing  a  solu- 
tion of  potassium  dichromate  by  excess  of  H,S04,  and  crystallizing: 
K2CrA+H2S04=K2S(Vr-H20+2Cr03 

It  crystallizes  in  deliquescent,  crimson  prisms,  very  soluble  in  ILO 


MANGANESE  131 

and  in  dilute  alcohol.    It  is  a  powerful  oxidant,  capable  of  igniting 
strong-  alcohol. 

The  true  chromic  acid  has  not  been  isolated,  but  salts  are  known 
which  correspond  to  three  acid  hydrates:  H2Cr04=chromic  acid; 
H2Cr207=dichromic  acid;  and  H2Cr3010=trichromic  acid. 

Sulphates. — A  violet  sulphate  crystallizes  in  octahedra,  (Cr)2 
(S04)3-|-15Aq,  and  is  very  soluble  in  H20.  At  100°  it  is  converted 
into  a  green  salt,  (Cr)2(S04)3+5Aq,  soluble  in  alcohol;  which,  at 
higher  temperatures,  is  converted  into  the  red,  insoluble,  anhydrous 
salt.  Chromic  sulphate  forms  double  sulphates,  containing  24  Aq, 
with  the  alkaline  sulphates.  (See  Alums.) 

Analytical  Characters. — CHROMOUS  SALTS. —  (1)  Potash:  a  brown 
ppt.  (2)  Ammonium  hydroxide:  greenish  white  ppt.  (3)  Alkaline 
sulphides:  black  ppt.  (4)  Sodium  phosphate:  blue  ppt. 

CHROMIC  SALTS.— (1)  Potash:  green  ppt.;  an  excess  of  precipitant 
forms  a  green  solution,  from  which  Cr203  separates  on  boiling.  (2) 
Ammonium  hydroxide:  greenish-gray  ppt.  (3)  Ammonium  sulphy- 
drate :  greenish  ppt. 

CHROMATES. —  (1)  H2S  in  acid  solution:  brownish  color,  changing 
to  green.  (2)  Ammonium  sulphydrate:  greenish  ppt.  (3)  Barium 
chloride:  yellowish  ppt.  (4)  Silver  nitrate:  brownish  red  ppt., 
soluble  in  HN03  or  NH4OH.  (5)  Lead  acetate :  yellow  ppt.,  soluble  in 
potash,  insoluble  in  acetic  acid. 

MANGANESE. 

$i/wboZ=Mn — Atomic  weight =55— (International=54:.93 )  — Mo- 
lecular weight=110.  Sp.  gr.=l.l38— 7.206. 

Occurs  chiefly  in  pyrolusite,  Mn02,  hausmanite,  Mn304,  braunite, 
Mn203,  and  manganite,  Mn203,  H20.  A  hard,  grayish,  brittle  metal; 
fusible  with  difficulty ;  obtained  by  reduction  of  its  oxides  by  C  at  a 
white  heat.  It  is  not  readily  oxidized  by  cold,  dry  air ;  but  is  super- 
ficially oxidized  when  heated.  It  decomposes  H20,  liberating  H,  and 
dissolves  in  dilute  acids. 

Oxides. — Manganese  forms  six  oxides,  or  compounds  representing 
them:  Manganous  oxide,  MnO;  manganous  manganic  oxide, 
Mn304 ;  manganic  oxide,  Mn203 ;  manganese  dioxide,  Mn02,  and 
manganese  heptoxide,  Mn207,  are  known  free.  Manganese  trioxide, 
Mn03,  has  not  been  isolated.  MnO  and  Mn203  are  basic ;  Mn304  and 
Mn02  are  indifferent  oxides;  and  Mn03  and  Mn207  are  anhydrides, 
corresponding  to  the  manganates  and  permanganates. 

Manganese  dioxide — Black  oxide  of  manganese — Mn02 — 86 — 
exists  in  nature  as  pyrolusite,  the  principal  ore  of  manganese,  in 
steel  gray,  or  brownish  black,  imperfectly  crystalline  masses. 

At  a  red  heat  it  loses  12  per  cent,  of  0:  3Mn02=Mn304+02 ;  and 


132  TEXT-BOOK  OP  CHEMISTRY 

at  a  white  heat,  a  further  quantity  of  0  is  given  off:  2Mn304= 
6MnO-f-(X.  Heated  with  H2S04,  it  gives  off  0,  and  forms  manga- 
nous  sulphate:  2MnO2+2H2S04=2MnS04+2H20+02.  With  H(11 
it  yields  manganous  chloride,  H20  and  Cl:  Mnb2+4HCl=MnCl2+ 
2H20-f  C12.  It  is  not  acted  on  by  HN03. 

The  precipitated  manganese  dioxide  ( Mangani  dioxidum  praecipi- 
tatum)  of  the  U.  S.  P.  contains  not  less  than  80  per  cent,  of  Mn02. 

Salts  of  Manganese. — Manganese  forms  two  series  of  salts: 
Manganous  salts,  containing  Mn";  and  manganic  salts,  containing 
(Mil.,)";  the  former  are  colorless  or  pink,  and  soluble  in  water;  the 
latter  are  unstable. 

Manganous  Sulphate — MnSO^+nAq — 150+?il8 — is  formed  by 
the  action  of  H2S04  on  Mn02.  Below  6°  it  crystallizes  with  7Aq, 
and  is  isomorphous  with  ferrous  sulphate;  between  7°-20°  it  forms 
crystals  with  5  Aq,  and  is  isomorphous  with  cupric  sulphate ;  between 
20°-30°  it  crystallizes  with  4  Aq.  It  is  rose-colored,  darker  as  the 
proportion  of  Aq  increases,  soluble  in  H20,  insoluble  in  alcohol.  With 
the  alkaline  sulphates  it  forms  double  salts,  with  6  Aq. 

Analytical  Characters. — MANGANOUS. —  (1)  Potash:  white  ppt., 
turning  brown.  (2)  Alkaline  carbonates:  white  ppts.  (3)  Ammo- 
nium sulphydrate:  flesh-colored  ppt.,  soluble  in  acids,  sparingly 
soluble  in  excess  of  precipitant.  (4)  Potassium  ferrocyanide :  faintly 
reddish  white  ppt.,  in  neutral  solution;  soluble  in  HC1.  (5)  Potas- 
sium cyanide:  rose-colored  ppt.  forming  brown  solution  with  excess. 

MANGANIC. — (1)  H,S:  ppt.  of  sulphur.  (2)  Ammonium  sulphy- 
drate: flesh-colored  ppt.  (3)  Potassium  ferrocyanide:  greenish  ppt. 
(4)  Potassium  f erricyanide :  brown  ppt.  (5)  Potassium  cyanide: 
light  brown  ppt. 

MANGANATES — are  green  salts,  whose  solutions  are  only  stable  in 
presence  of  excess  of  alkali,  and  turn  brown  when  diluted  and  acidu- 
lated. 

PERMANGANATES — form  red  solutions,  which  are  decolorized  by 
S02,  other  reducing  agents,  and  many  organic  substances. 

IRON. 

Symbol— ~FQ  (Ferrum) — Atomic  weight—^ — (International^ 
55.84)—  Molecular  weight- 112.  8p.  gr.=7.25—1.9. 

Occurrence. — Free,  in  small  quantity  only,  in  platinum  ores  and 
meteorites.  As  Fe203  in  red  hematite  and  specular  iron;  as  hydrates 
of  Fe203  in  brown  hematite  and  oolitic  iron;  as  Fe304  in  magnetic 
iron;  as  FeCO3  in  spathic  iron,  clay  ironstone  and  bog  ore;  and  as 
FeS2  in  pyrites.  It  is  also  a  constituent  of  most  soils  and  clays,  exists 
in  many  mineral  waters,  and  in  the  red  blood  pigment  of  animals. 

Preparation. — In  working  the  ores,  reduction  is  first  effected  in  a 


IRON  133 

blast  furnace,  into  which  alternate  layers  of  ore,  coal  and  limestone 
are  fed  from  the  top  while  air  is  forced  in  from  below.  In  the  lower 
part  of  the  furnace  CO,  is  produced,  at  the  expense  of  the  coal; 
higher  up  it  is  reduced  by  the  incandescent  fuel  to  CO,  which,  at  a 
still  higher  point,  reduces  the  ore: 

Fe203+3C=3CO+Fe2 

The  fused  metal,  so  liberated,  collects  at  the  lowest  point,  under 
a  layer  of  slag;  and  is  drawn  off  to  be  cast  as  pig  iron.  This  product 
is  then  purified,  by  burning  out  impurities,  in  the  process  known  as 
puddling. 

Pure  iron  is  prepared  by  reduction  of  ferrous  chloride,  or  of  ferric 
oxide,  by  H  at  a  temperature  approaching  redness. 

Varieties. — Cast  iron  is  a  brittle,  white  or  gray,  crystalline  metal, 
consisting  of  Fe  89-90% ;  C  1-4.5% ;  and  Si,  P,  S,  and  Mn.  As  pig 
iron,  it  is  the  product  of  the  blast-furnace. 

Wrought,  or  bar  iron,  is  a  fibrous,  tough  metal,  freed  in  part  from 
the  impurities  of  cast  iron,  by  refining  and  puddling. 

Steel  is  Fe  combined  with  a  quantity  of  C,  less  than  that  existing 
in  cast  iron,  and  greater  than  that  in  bar  iron.  It  is  prepared  by 
cementation;  which  consists  in  causing  bar  iron  to  combine  with  C; 
or  by  the  Bessemer  method;  which,  as  now  used,  consists  in  burning 
the  C  out  of  molten  cast  iron,  to  which  the  proper  proportion  of  C  is 
then  added  in  the  shape  of  spiegel  eisen,  an  iron  rich  in  Mn  and  C. 

The  purest  forms  of  commercial  iron  are  those  used  in  piano- 
strings,  the  teeth  of  carding  machines  and  electro  magnets ;  known  as 
soft  iron. 

Reduced  iron — Ferrum  reductum  (U.S.  P.) — is  Fe,  more  or  less 
mixed  with  Fe203  and  Fe304,  obtained  by  heating  Fe203  in  H : 
Fe203+3H2=3H20+Fe2 

The  official  ferrum  reductum  contains  not  less  than  90  per  cent, 
of  metallic  iron. 

Properties. — Physical. — Pure  iron  is  silver  white,  quite  soft; 
crystallizes  in  cubes  or  octahedra.  Wrought  iron  is  gray,  hard,  very 
tenacious,  fibrous,  quite  malleable  and  ductile,  capable  of  being 
welded,  highly  magnetic,  but  only  temporarily  so.  Steel  is  gray,  very 
hard  and  brittle  if  tempered,  soft  and  tenacious  if  not,  permanently 
magnetic. 

Chemical. — Iron  is  not  altered  by  dry  air  at  the  ordinary  tem- 
perature. At  a  red  heat  it  is  oxidized.  In  damp  air  it  is  converted 
into  a  hydrate,  iron  rust.  Tinplate  is  sheet  iron,  coated  with  tin; 
galvanized  iron  is  coated  with  zinc,  to  preserve  it  from  the  action  of 
damp  air. 

Iron  unites  directly  with  Cl,  Br,  I,  S,  N,  P,  As,  and  Sb.  It  dis- 
solves in  HC1  as  ferrous  chloride,  while  H  is  liberated.  Heated  with 
strong  H2S04  it  gives  off  S02 ;  with  dilute  H2S04,  H  is  given  off  and 


134  TEXT-BOOK   OF   CHEMISTRY 

ferrous  sulphate  formed.  Dilute  HNO.{  dissolves  Fe,  but  the  concen- 
trated acid  renders  it  passive,  when  it  is  not  dissolved  by  either  con- 
centrated or  dilute  HN03,  until  the  passive  condition  is  destroyed  by 
contact  with  Pt,  Ag  or  Cu,  or  by  heating  to  40°. 

Compounds  of  Iron. — Oxides. — Three  oxides  of  iron  exist  free: 
FeO  ;  Fe2O3 ;  Fe3O4. 

Ferrous  Oxide. — Protoxide  of  iron — FeO — 72 — is  formed  by  heat- 
ing Fe203  in  CO  or  CO,. 

Ferric  Oxide. — Sesquioxide  or  peroxide  of  iron — Fe203 — 160 — 
occurs  in  nature  (see  above),  and  is  formed  when  ferrous  sulphate 
is  strongly  heated,  as  in  the  manufacture  of  pyrosulphuric  acid.  It 
is  a  reddish,  amorphous  solid,  is  a  weak  base,  and  is  decomposed 
at  a  white  heat  into  0  and  Fe304. 

Magnetic  Oxide — Ferroso-ferric  oxide — Black  oxide — Fe304— 
232 — is  the  natural  loadstone,  and  is  formed  by  the  action  of  air, 
or  steam,  upon  iron  at  high  temperatures.  It  is  probably  a  com- 
pound of  ferrous  and  ferric  oxides  (FeO,  Fe203),  as  acids  produce 
with  it  mixtures  of  ferrous  and  ferric  salts. 

Hydroxides — Ferrous. — When  a  solution  of  a  ferrous  salt  is  de- 
composed by  an  alkaline  hydroxide,  a  greenish-white  hydroxide, 
Fe(OH)2  is  deposited;  which  rapidly  absorbs  0  from  the  air,  with 
formation  of  ferric  hydroxide. 

Ferric. — When  an  alkali  is  added  to  a  solution  of  a  ferric  salt,  a 
brown,  gelatinous  precipitate  is  formed,  which  is  ferric  hydroxide, 
Fe(OH)3: 

2FeCl3+6NH4OH=6NH4Cl+2Fe(OH)3 

It  is  not  formed  in  the  presence  of  fixed  organic  acids  or 
of  sugar  in  sufficient  quantity.  If  preserved  under  H20,  it  is 
partly  oxidized,  forming  an  oxyhydrate  which  is  incapable  of  forming 
ferrous  arsenate  with  As203.  (See  p.  115.) 

If  recently  precipitated  ferric  hydroxide  is  dissolved  in  solution  of 
ferric  chloride  or  acetate,  and  subjected  to  dialysis,  almost  all  the  acid 
passes  out,  leaving  in  the  dialyzer  a  dark  red  solution,  which  prob- 
ably contains  this  colloid  hydrate,  and  which  is  instantly  coagulated 
by  a  trace  of  H2S04,  by  alkalies,  many  salts,  and  by  heat;  dialyzed 
iron. 

Sulphides. — Ferrous  Sulphide — Protosulphide  of  iron — FeS — 88 
—is  formed : 

(1)  By  heating  a  mixture  of  finely-divided  Fe  and  S  to  redness; 
(2)  by  pressing  roll-sulphur  on  white-hot  iron;  (3)  in  a  hydnitcd 
condition,  FeS,  H20,  by  treating  a  solution  of  a  ferrous  salt  with  an 
alkaline  sulphydrate. 

The  dry  sulphide  is  a  brownish,  brittle,  magnetic  solid,  insoluble 
in  ILO,  soluble  in  acids  with  evolution  of  H2S.  The  hydrate  is  a 
black  powder,  which  absorbs  0  from  the  air,  turning  yellow,  by 


IRON  135 

formation  of  Fe203,  and  liberation  of  S.     It  occurs  in  the  feces  of 
persons  .taking  chalybeate  waters  or  preparations  of  iron. 

Ferric  Sulphide— Sesquisulphide — Fe,S3 — 208 — occurs  in  nature 
in  copper  pyrites,  and  is  formed  when  the  disulphide  is  heated  to 
redness. 

Ferric  Disulphide — FeS2 — 120 — occurs  in  the  white  and  yellow 
Martial  pyrites,  used  in  the  manufacture  of  H2S04.     When  heated 
in  air,  it  is  decomposed  into  S02  and  magnetic  pyrites: 
3FeS2+202=Fe3S4+2SO2 

Chlorides.  —  Ferrous  Chloride— Protochloride—FeC\2— 127— is 
produced:  (1)  by  passing  dry  HC1  over  red-hot  Fe;  (2)  by  heating 
ferric  chloride  in  H. 

The  anhydrous  compound  is  a  yellow,  crystalline,  volatile,  and 
very  soluble  solid.  The  hydrated  is  in  greenish,  oblique  rhombic 
prisms,  deliquescent  and  very  soluble  in  H20  and  alcohol.  When 
heated  in  air  it  is  converted  into  ferric  chloride,  and  an  oxy- 
chloride. 

Ferric    Chloride — Sesquichloride — Perchloride — Ferri    chloridum 
(U.  S.  P.) — FeCl3  is  produced  by  heating  FeCl2  in  aqua  regia: 
3FeCl2+HNO3+3HCl=2H20+NO+3FeCl3 

(2)  By  dissolving  ferric  hydroxide  in  HC1;  (3)  by  the  action  of 
Cl  or  of  HNO3  on  solution  of  ferrous  chloride. 

The  anhydrous  compound  forms  reddish-violet,  crystalline  plates, 
very  deliquescent.  The  hydrates  form  yellow,  nodular,  imperfectly 
crystalline  masses,  or  rhombic  plates,  very  soluble  in  H20,  soluble  in 
alcohol  and  ether.  In  solution,  it  is  converted  into  FeCl2  by  reducing 
agents.  The  Liquor  ferri  chloridi  (U.  S.  P.)  is  an  aqueous  solution 
of  this  compound,  containing  excess  of  acid.  The  Tincture  ferri 
chloridi  (U.  S.  P.)  is  the  solution,  diluted  with  alcohol. 

Sulphates. — Ferrous  Sulphate — ProtosulpJiate — Green  vitriol — 
Copperas— Ferri  sulphas  (U.  S.  P.)—  FeS04+7Aq— 152+126— is 
formed:  (1)  by  oxidation  of  the  sulphide,  Fe3S4,  formed  in  the  manu- 
facture of  H2S04;  (2)  by  dissolving  Fe  in  dilute  H2S04. 

It  forms  green,  efflorescent,  oblique  rhombic  prisms,  quite  soluble 
in  H20,  insoluble  in  alcohol.  It  loses  6  Aq  at  100°  (Ferri  sulphas 
exsiccatus,  U.  S.  P.)  ;  and  the  last  Aq  at  about  300°.  At  a  red 
heat  it  is  decomposed  into  Fe203;  S02  and  S03.  By  exposure  to 
air  it  is  gradually  converted  into  a  basic  ferric  sulphate  Fe2(S04)3, 
5Fe203. 

Ferric  Sulphates  are  quite  numerous,  and  are  formed  by  oxida- 
tions of  ferrous  sulphate  under  different  conditions.  The  normal  sul- 
phate, (Fe2)(S04)3,  is  formed  by  treating  solution  of  FeS04  with 
HN03,  and  evaporating,  after  addition  of  one  molecule  of  H2S04  for 
each  two  molecules  of  FeS04.  The  Liquor  ferri  tersulphatis  (U.  S. 
P.),  contains  this  salt.  It  is  a  yellowish  white,  amorphous  solid. 


136  TEXT-BOOK   OF   CHEMISTRY 

Of  the  many  basic  ferric  sulphates,  the  only  one  of  medical  in- 
terest is  Monsel's  salt,  5Fe2(S04)3+4Fe.,03,  which  exists  in  the 
Liquor  ferri  subsulphatis  (U.  S.  P.).  Its  solution  is  decolorized,  and 
forms  a  white  deposit  with  excess  of  H2S04. 

Phosphates.— Triferrous  Phosphater-Fe3(P04)2— 358.— A  white 
precipitate,  formed  by  adding  disodic  phosphate  to  a  solution  of  a 
ferrous  salt,  in  presence  of  sodium  acetate.  By  exposure  to  air  it 
turns  blue;  a  part  being  converted  into  ferric  phosphate.  It  is 
insoluble  in  H20 ;  sparingly  soluble  in  H20  containing  carbonic  or 
acetic  acid. 

It  is  probably  this  phosphate,  capable  of  turning  blue,  which 
sometimes  occurs  in  the  lungs  in  phthisis,  in  blue  pus,  and  in  long- 
buried  bones. 

Ferric  Phosphate — FeP04 — 151 — is  produced  by  the  action  of 
an  alkaline  phosphate  on  ferric  chloride.  It  is  soluble  in  HC1,  HN03, 
citric  and  tartaric  acids,  insoluble  in  phosphoric  acid  and  in  solu- 
tion of  disodic  phosphate.  The  ferri  phosphas  (U.  S.  P.)  is  a  com- 
pound, or  mixture  of  this  salt  with  disodic  citrate,  which  is  soluble 
in  water. 

There  exist  quite  a  number  of  basic  ferric  phosphates. 

Acetates. — Ferrous  Acetate — Fe(C2H3O2)2 — 174 — is  formed  by  decomposi- 
tion of  ferrous  sulphate  by  calcium  acetate,  in  soluble,  silky  needles. 

Ferric  Acetates. — The  normal  salt  Fe(C2H3O2)3,  is  obtained  by  adding 
slight  excess  of  ferric  sulphate  to  lead  acetate,  and  decanting  after  twenty-four 
hours.  It  is  dark-red,  uncrystallizable,  very  soluble  in  alcohol,  and  in  H20.  If 
its  solution  be  heated  it  darkens  suddenly,  gives  off  acetic  acid,  and  contains  a 
basic  acetate.  When  boiled,  it  loses  all  its  acetic  acid,  and  deposits  ferric 
hydrate.  When  heated  in  closed  vessels  to  100°,  and  treated  with  a  trace  of 
mineral  acid,  it  deposits  the  modified  ferric  hydrate. 

Ferrous  Carbonate — FeC03 — Spathic  iron — 116 — occurs  as  an 
ore  of  iron,  and  is  obtained,  in  a  hydrated  form,  by  adding  an 
alkaline  carbonate  to  a  ferrous  salt.  It  is  a  greenish,  amorphous 
powder,  which  on  exposure  to  air  turns  red  by  formation  of  ferric 
hydrate ;  a  change  which  is  retarded  by  the  presence  of  sugar,  hence 
the  addition  of  that  substance  in  the  ferri  carbonas  saccharatus  (U. 
S.  P.).  It  is  insoluble  in  pure  H20,  but  soluble  in  H20  containing 
carbonic  acid,  probably  as  ferrous  bicarbonate,  H2Fe(C03)2,  in 
which  form  it  occurs  in  chalybeate  waters. 

Citrates.— Ferric  Citrate— Fe2  ( C6H8O, )  2+6Aq— 490+  108— is  in  garnet- 
colored  scales,  obtained  by  dissolving  ferric  hydrate  in  solution  of  citric  acid, 
and  evaporating  the  solution  at  about  60°.  It  loses  3Aq  at  120°,  and  the  re- 
mainder at  150°.  If  a  small  quantity  of  ammonium  hydroxide  is  added,  before 
the  evaporation,  the  product  consists  of  the-  modified  citrater=ferri  et  ammonii 
citras  (U.  S.  P.),  which  only  reacts  with  potassium  ferrocyanide  after  addition 
of  HC1. 

The  various  citrates  of  iron  and  alkaloids  are  not  definite  compounds. 

Ferric  Ferrocyanide— Prussian  blue—  (Fe2)2(FeCflNa)3+18Aq— 860+324— 
is  a  dark-blue  precipitate,  formed  when  potassium  ferrocyanide  is  added  to  a 


URANIUM  137 

ferric  salt.    It  is  insoluble  in  HaO,  alcohol  and  dilute  acids;   soluble  in  oxalic 
acid  solution    (blue  ink).     Alkalies  turn  it  brown. 

Ferrous  Ferricyanide — Turnbull's  blue — Fe»[Fe(CN)6]a-j-nAq— 592-|-nl8 
— is  a  dark  blue  substance  produced  by  the  action  of  potassium  ferricyanide  on 
ferrous  salts.  Heated  in  air  it  is  converted  into  Prussian  blue  and  ferric  oxide. 

General  methods  of  oxidizing  a  ferrous  salt  to  the  ferric  state. 
(1)  By  passing  chlorine  gas  through  a  solution  of  the  ferrous  salt: 

2FeCl2+Cl2==2FeCla 

6FeS04+3Cl2=2FeCi8+2Fe2(S04)8 

(2)  By  heating  a  solution  of  the  ferrous  salt  with  nitric  acid : 

3FeCl2+4HN03=Fe  (N08)  2+NO+2H20+2FeCl3 
3FeS04+4HN03=Fe  (N03)  2+NO+2H20+Fe2  ( S04) , 
General  methods  of  reducing  a  ferric  salt  to  the  ferrous,  state. 

(1)  By  adding  zinc  and  hydrochloric  acid  to  a  solution  of  a  ferric 
salt ;  the  nascent  hydrogen  which  is  liberated  will  effect  the  reduction  :f 

2FeCl3+H2=2HCl+2FeCl2 

(2)  By  passing  sulphuretted  hydrogen  through  a  solution  of  a 
ferric  salt: 

4FeCl3-f2H2S=S2+4HCl+4FeCl2 

Analytical  Characters. — FERROUS — Are  acid;  colorless  when  an- 
hydrous, pale  green  when  hydrated;  oxidized  by  air  to  basic  ferric 
compounds.  (1)  Potash:  greenish  white  ppt. ;  insoluble  in  excess; 
changing  to  green  or  brown  in  air.  (2)  Ammonium  hydroxide; 
greenish  ppt. ;  soluble  in  excess ;  not  formed  in  presence  of  ammo- 
niacal  salts.  (3)  Ammonium  sulphydrate:  black  ppt.;  insoluble  in 
excess;  soluble  in  acids.  (4)  Potassium  ferrocyanide  (in  absence  of 
ferric  salts)  :  white  ppt.;  turning  blue  in  air.  (5)  Potassium  ferri- 
cyanide :  blue  ppt. ;  soluble  in  KOH ;  insoluble  in  HC1. 

FERRIC — Are  acid,  and  yellow  or  brown.  (1)  Potash,  or  ammo- 
nium hydroxide :  voluminous,  red-brown  ppt. ;  insoluble  in  excess. 

(2)  Hydrogen  sulphide,   in  acid  solution:  milky  ppt.   of  sulphur; 
ferric  reduced  to  ferrous  compound.     (3)   Ammonium  sulphydrate: 
black  ppt. ;  insoluble  in  excess;  soluble  in  acids.    (4)  Potassium  ferro- 
cyanide: dark  blue  ppt.;  insoluble  in  HC1;  soluble  in  KOH.     (5) 
Potassium  thiocyanate :  dark-red  color ;  prevented  by  tartaric  or  citric 
acid;    discharged   by   mercuric   chloride.      (6)    Tannin:   blue-black 
color. 

III.    URANIUM  GROUP. 
URANIUM. 

Symbol—^— Atomic  weig~kt=238—(International=2383)—Sp. 
gr.=lSA. 

This  element  is  usually  classed  with  Fe  and  Cr,  or  with  Ni  and 
Co.  It  does  not,  however,  form  compounds  resembling  the  ferric;  it 


138  TEXT-BOOK   OF   CHEMISTRY 

forms  a  series  of  well-defined  uranates,  and  a  series  of  compounds  of 
the  radical  uranyl  (UO)'.  Uranium  nitrate,  Uranii  nitras,  (U.  S.  P.) 
contains  not  less  than  98  per  cent,  of  U02(N03)2-{-6Aq.  (uranyl 
nitrate).  Standard  solutions  of  its  acetate  or  nitrate  are  used  for 
the  quantitative  determination  of  H3P04. 


IV.    LEAD  GROUP. 
LEAD. 

^Pb  (Plumbum) — Atomic  weight=201 — (International^ 
207.20)— Molecular  weight=414:—Sp.  #r.=11.445. 

Lead  is  usually  classed  with  Cd,  Bi,  or  Cu  and  Hg.  It  differs, 
however,  from  Bi  in  being  bivalent  or  quadrivalent,  but  not  triva- 
lent,  and  in  forming  no  compounds  resembling  those  of  bismuthyl 
(BiO)  ;  from  Cd,  in  the  nature  of  its  0  compounds;  and  from  Cu  and 
Hg  in  forming  no  compounds  similar  to  the  mercurous  and  cuprous 
salts.  Indeed,  the  nature  of  the  Pb  compounds  is  such  that  the 
element  is  best  classed  in  a  group  by  itself,  which  finds  a  place  in 
this  class  by  virtue  of  the  existence  of  potassium  plumbate. 

Occurrence. — Its  most  abundant  ore  is  galena,  PbS.  It  also 
occurs  in  white  lead  ore,  PbC03,  in  anglesite,  PbS04,  and  in  horn 
lead,  PbCl2. 

Preparation. — Galena  is  first  roasted  with  a  little  lime.  The  mix- 
ture of  PbO,  PbS,  and  PbS04  obtained  is  strongly  heated  in  a  rever- 
beratory  furnace,  when  S02  is  driven  off: 

2PbO+PbS=S02+3Pb  and 
PbS+PbS04=2S02+2Pb 

The  impure  work  lead,  so  formed,  is  purifie'd  by  fusion  in  air,  and 
removal  of  the  film  of  oxides  of  Sn  and  Sb.  If  the  ore  is  rich  in 
Ag,  that  metal  is  extracted,  by  taking  advantage  of  the  greater  fusi- 
bility of  an  alloy  of  Pb  and  Ag,  than  of  Pb  alone;  and  subsequent 
oxidation  of  the  remaining  Pb. 

Properties.— Physical. — It  is  a  bluish  white  metal;  brilliant  upon 
freshly  cut  surfaces;  very  soft  and  pliable;  not  very  malleable  or 
ductile;  crystallizes  in  octahedra;  a  poor  conductor  of  electricity;  a 
better  conductor  of  heat.  When  expanded  by  heat  it  does  not,  on 
cooling,  return  to  its  original  volume. 

Chemical. — When  exposed  to  air  it  is  oxidized,  more  readily  and 
completely  at  high  temperatures.  The  action  of  H,0  on  Pb  varies 
with  the  conditions.  (See  p.  67.)  Pure  unaerated  H20  has  no  action 
upon  it.  By  the  combined  action  of  air  and  moisture  Pb  is  oxidi/rd, 
and  the  oxide  dissolved  in  the  H20,  leaving  a  metallic  surface  for  the 
contimumrc  of  the  action.  The  solvent  action  of  H20  upon  Pb  is 


LEAD  139 

increased,  owing  to  the  formation  of  basic  salts,  by  the  presence  of 
nitrogenized  organic  substances,  nitrates,  nitrites,  and  chlorides.  On 
the  other  hand,  carbonates,  sulphates,  and  phosphates,  by  their  ten- 
dency to  form  insoluble  coatings,  diminish  the  corroding  action  of 
H20.  Carbonic  acid  in  small  quantity,  especially  in  presence  of 
carbonates,  tends  to  preserve  Pb  from  solution,  while  H20  highly 
charged  with  it  (soda  water)  dissolves  the  metal  readily.  Lead  is 
dissolved,  as  a  nitrate,  by  HN03.  H2S04,  when  cold  and  moderately 
concentrated,  does  not  affect  it;  but,  when  heated,  dissolves  it  the 
more  readily  as  the  acid  is  more  concentrated.  It  is  attacked  by 
HC1  of  sp.  gr.  1.12,  especially  if  heated.  Acetic  acid  dissolves  it  as 
acetate,  or,  in  the  presence  of  CO,,  converts  it  into  white  lead. 

Oxides. — Lead  Monoxide — Massicot — Litharge — Plumbi  oxidum 
(U.  S.  P.) — PbO — 223 — is  prepared  by  heating  Pb,  or  its  carbonate, 
or  nitrate,  in  air.  If  the  product  has  been  fused,  it  is  litharge;  if 
not,  massicot.  It  forms  copper-colored,  mica-like  plates,  or  a  yellow 
powder;  or  crystallizes,  from  its  solution  in  soda  or  potash,  in  white, 
rhombic  dodecahedra,  or  in  rose-colored  cubes.  It  fuses  near  a  red 
heat,  and  volatilizes  at  a  white  heat;  sp.  gr.  9.277 — 9.5.  It  is  spar- 
ingly soluble  in  H20,  forming  an  alkaline  solution. 

Heated  in  air  to  300°  it  is  oxidized  to  minium.  It  is  readily 
reduced  by  H  or  C.  With  Cl  it  forms  PbCl,  and  0.  It  is  a  strong 
base;  decomposes  alkaline  salts,  with  liberation  of  the  alkali.  It  dis- 
solves in  HN03,  and  in  hot  acetic  acid,  as  nitrate  or  acetate.  When 
ground  up  with  oils  it  saponifies  the  glycerol  ethers,  the  Pb  combining 
with  the  fatty  acids  to  form  Pb  soaps,  one  of  which,  lead  oleate,  is 
the  emplastrum  plumbi,  lead  plaster,  diachylon  plaster  (U.  S.  P.). 
It  also  combines  with  the  alkalies  and  earths  to  form  plumbites. 
Calcium  plumbite,  CaPb,03,  is  a  crystalline  salt,  formed  by  heating 
PbO  with  milk  of  lime,  and  used  in  solution  as  a  hair  dye. 

Plumboso-plumbic  Oxide — Red  oxide — Minium — Red  lead — Pb304 — 685 — 
is  prepared  by  heating  massicot  to  300°  in  air.  It  ordinarily  has  the  composi- 
tion Pb304,  and  has  been  considered  as  composed  of  PbO2,  2PbO;  or  a  basic 
lead  salt  of  plumbic  acid,  Pb03Pb,  PbO.  An  orange-colored  variety  is  formed 
when  lead  carbonate  is  heated  to  300°. 

It  is  a  bright  red  powder,  sp.  gr.  8.62.  It  is  converted  into  PbO  when 
strongly  heated,  or  by  the  action  of  reducing  agents.  HN03  changes  its  color 
to  brown,  dissolving  PbO  and  leaving  Pb02.  It  is  decomposed  by  HC1,  with 
formation  of  PbCl2,  H2O  and  Cl. 

Lead  Dioxide. — Plumbic  anhydride — Pb02 — 239 — is  prepared, 
either  by  dissolving  the  PbO  out  of  red  lead  by  dilute  HN03,  or  by 
passing  a  current  of  Cl  through  H20,  holding  lead  carbonate  in  sus- 
pension. 

It  is  a  dark,  reddish  brown,  amorphous  powder;  sp.  gr.  8.903- 
9.190 ;  insoluble  in  H20.  Heated,  it  loses  half  its  0,  and  is  converted 


140  TEXT-BOOK   OF   CHEMISTRY 

into  PbO.  It  is  a  valuable  oxidant.  It  absorbs  S02  to  form.  PbS04. 
It  combines  with  alkalies  to  form  plumbates,  M2Pb03. 

Lead  Sulphide — Galena — PbS — 239 — exists  in  nature.  It  is  also 
formed  by  direct  union  of  Pb  and  S;  by  heating  PbO  with  S,  or 
vapor  of  CS2 ;  or  by  decomposing  a  solution  of  a  Pb  salt  by  H2S  or 
an  alkaline  sulphide. 

The  native  sulphide  is  a  bluish  gray,  and  has  a  metallic  luster; 
sp.  gr.  7.58;  that  formed  by  precipitation  is  a  black  powder;  sp.  gr. 
6.924.  It  fuses  at  a  red  heat  and  is  partly  sublimed,  partly  converted 
into  a  subsulphate.  Heated  in  air  it  is  converted  into  PbS04,  PbO 
and  S02.  Heated  in  H  it  is  reduced.  Hot  HN03  oxidizes  it  to 
PbS04.  "Hot  HC1  converts  it  into  PbCl2.  Boiling  H,S04  converts  it 
into  PbS04  and  S02. 

Lead  Chloride — PbCl2 — 278 — is  formed  by  the  action  of  Cl  upon  Pb  at  a 
red  heat;  by  the  action  of  boiling  HC1  upon  Pb,  and  by  double  decomposition 
between  a  lead  salt  and  a  chloride. 

It  crystallizes  in  plates,  or  hexagonal  needles;  sparingly  soluble  in  cold 
H2O,  less  soluble  in  H2O  containing  HC1;  more  soluble  in  hot  H2O,  and  in  con- 
centrated HC1. 

Several  oxychlorides  are  known.  Cassel,  Paris,  Verona,  or  Turner's 
yellow  is  PbCl2,  7PbO. 

Lead  Iodide — PbI2 — 461 — is  deposited,  as  a  bright  yellow  powder,  when 
a  solution  of  potassium  iodide  is  added  to  a  solution  of  Pb  salt.  Fused  in  air, 
it  is  converted  into  an  oxyiodide.  Light  and  moisture  decompose  it,  with 
liberation  of  I.  It  is  almost  insoluble  in  H2O,  soluble  in  solutions  of  ammonium 
chloride,  sodium  hyposulphite,  alkaline  iodide,  and  potash. 

Salts  of  Lead.— Nitrates.— Lead  Nitrate— Pb( NO 3)2— is  formed 
by  solution  of  Pb,  or  of  its  oxides,  in  excess  of  HN03.  It  forms 
anhydrous  crystals;  soluble  in  H20.  Heated,  it  is  decomposed  into 
PbO,  0  and  N02. 

Lead  Sulphate. — PbS04 — 303 — is  formed  by  the  action  of  hot 
concentrated  H2S04  on  Pb;  or  by  double  decomposition  between  a 
sulphate  and  a  Pb  salt  in  solution.  It  is  a  white  powder,  almost  in- 
soluble in  H20,  soluble  in  concentrated  H2S04,  from  which  it  is  de- 
posited by  dilution. 

Lead  Chromate — Chrome  yellow — PbCr04 — 323 — is  formed  by 
decomposing  Pb(N03)2  with  potassium  chromate.  It  is  a  yellow, 
amorphous  powder,  insoluble  in  H20,  soluble  in  alkalies. 

Acetates.— Lead  Acetate— Salt  of  Saturn— Sugar  of  Lead— 
Plumbi  acetas  (U.  S.  P.)—  Pb(C2H302),+3Aq— 325+54— is  formed 
by  dissolving  PbO  in  acetic  acid ;  or  by  exposing  Pb  in  contact  with 
acetic  acid  to  air. 

It  crystallizes  in  large,  oblique  rhombic  prisms,  sweetish,  with  a 
metallic  after-taste;  soluble  in  H20  and  alcohol;  its  solutions  being 
;icid.  In  air  it  effloresces,  and  is  superficially  converted  into  car- 
bonate. It  fuses  at  75.5°;  loses  Aq  and  a  part  of  its  acid  at  100°, 
fnnning  the  sesquibasic  acetate,  2[Pb(C2H302)2]Pb(OH)2;  at  280° 


LEAD  141 

it  enters  into  true  fusion,  and,  at  a  slightly  higher  temperature,  is 
decomposed  into  C02,  Pb,  and  acetone.  Its  aqueous  solution  dis- 
solves PbO,  with  formation  of  basic  acetates. 

Sexbasic  Lead  Acetate— Pb(C2H302)  OH,  2PbO— 729— is  the 
main  constituent  of  Goulard's  extract=Liquor  plumbi  subacetatis 
(U.  S.  P.),  and  is  formed  by  boiling  a  solution  of  the  neutral  acetate 
'with  PbO  in  fine  powder.  It  contains  18  per  cent,  of  Pb.  The  solu- 
tion becomes  milky  on  addition  of  ordinary  H20,  from  formation  of 
the  sulphate  and  carbonate.  The  liquor  plumbi  subacetatis  dilutus 
(U.  S.  P.)  contains  4  parts  of  the  liquor  plumbi  subacetatis  in  100 
parts  of  water. 

Lead  Carbonate — PbC03 — 267 — occurs  in  nature  as  cerusite ;  and 
is  formed,  as  a  white,  insoluble  powder,  when  a  solution  of  a  Pb  com- 
pound is  decomposed  by  an  alkaline  carbonate,  or  by  passing  C02 
through  a  solution  containing  Pb. 

White  lead  or  ceruse,  or  plumbi  carbonas,  is  a  basic  carbonate 
(PbC03)2,  Pb(OH)2 — 775 — mixed  with  varying  proportions  of  other 
basic  carbonates.  It  is  usually  prepared  by  the  action  of  C02  on  a  solu- 
tion of  the  subacetate,  prepared  by  the  action  of  acetic  acid  on  Pb  and 
PbO.  It  is  a  heavy,  white  powder,  insoluble  in  H20,  except  in  the 
presence  of  C02 ;  soluble  in  acids  with  effervescence ;  and  decomposed 
by  heat  into  C02  and  PbO.  White  lead  enters  into  the  composition 
of  almost  all  oil-paints,  being  used  to  dilute  other  pigments.  The 
darkening  of  oil-paintings  is  due  to  the  formation  of  the  black  lead 
sulphide  by  atmospheric  H2S. 

Analytical  Characters. — (1)  Hydrogen  sulphide,  in  acid  solution: 
a  black  ppt. ;  insoluble  in  alkaline  sulphides,  and  in  cold,  dilute  acids. 
(2)  Ammonium  sulphydrate:  black  ppt.;  insoluble  in  excess.  (3) 
Hydrochloric  acid:  white  ppt.,  in  not  too  dilute  solution;  soluble  in 
boiling  H20.  (4)  Ammonium  hydroxide:  white  ppt.;  insoluble  in 
excess.  (5)  Potash:  white  ppt.;  soluble  in  excess,  especially  when 
heated.  (6)  Sulphuric  acid:  white  ppt.;  insoluble  in  weak  acids,  sol- 
uble in  solution  of  ammonium  tartrate.  (7)  Potassium  iodide:  yel- 
low ppt. ;  sparingly  soluble  in  boiling  H20 ;  soluble  in  large  excess. 

(8)  Potassium   chromate:    yellow   ppt.;   soluble   in   KOH   solution. 

(9)  Iron  or  zinc  separate  the  element  from  solution  of  its  salts. 

Action  on  the  Economy. — All  the  soluble  compounds  of  Pb,  and  those 
which,  although  not  soluble,  are  readily  convertible  into  soluble  compounds  by 
H20,  air,  or  the  digestive  fluids,  are  actively  poisonous.  Some  are  also  in- 
jurious by  their  local  action  upon  tissues  with  which  they  come  in  contact; 
such  are  the  acetate,  and,  in  less  degree,  the  nitrate. 

The  chronic  form  of  lead  intoxication,  painter's  colic,  etc.,  is  purely 
poisonous,  and  is  produced  by  the  continued  absorption  of  minute  quantities 
of  Pb,  either  by  the  skin,  lungs,  or  stomach.  The  acute  form  presents  symptoms 
referable  to  the  local,  as  well  as  to  the  poisonous,  action  of  the  Pb  salt,  and  is 
usually  caused  by  the  ingestion  of  a  single  dose  of  the  acetate  or  carbonate. 

Metallic  Pb,  although  probably  not  poisonous  of  itself,  causes  chronic  lead- 


142  TEXT-BOOK   OF   CHEMISTRY 

poisoning  by  the  readiness  with  which  it  is  convertible  into  compounds  capable 
of  absorption.  The  principal  sources  of  poisoning  by  metallic  Pb  are:  the  con- 
tamination of  drinking  water  which  has  been  in  contact  with  the  metal  (see 
p.  67);  the  use  of  articles  of  food,  or  of  chewing  tobacco,  which  has  birn 
packed  in  tin-foil,  containing  an  excess  of  Pb;  the  drinking  of  beer  or  other 
beverages  which  have  been  in  contact  with  pewter;  or  the  handling  of  the 
metal  and  its  alloys. 

Almost  all  the  compounds  of  Pb  may  produce  painter's  colic.  The  car- 
bonate, in  painters,  artists,  manufacturers  of  white  lead,  and  in  persons  sleep- 
ing in  newly-painted  rooms;  the  oxides,  in  the  manufactures  of  glass,  pottery, 
sealing-wax,  and  litharge,  and  by  the  use  of  lead-gla/.ed  pottery;  by  other  com- 
pounds, by  the  inhalation  of  the  dust  of  cloth  factories,  and  by  the  use  of  lead 
hair-dyes. 

Acute  lead-poisoning  is  of  by  no  means  as  common  occurrence  as  the 
chronic  form,  and  usually  terminates  in  recovery.  It  is  caused  by  the  ingestion 
of  a  single  dose  of  the  acetate,  subacetate,  carbonate,  or  of  red  lead.  In 
such  cases  the  administration  of  magnesium  sulphate  is  indicated;  it  enters  into 
double  decomposition  with  Pb  salt  to  form  the  insoluble  PbS04. 

Lead,  once  absorbed,  is  eliminated  very  slowly,  it  becoming  fixed  by  com- 
bination with  the  proteins,  a  form  of  combination  which  is  rendered  soluble  by 
potassium  iodide.  The  channels  of  elimination  are  by  the  perspiration,  urine 
and  bile. 


V.  BISMUTH  GROUP. 
BISMUTH. 

Symbol=Bi — Atomic  weight=20S — Molecular  weight=416. — Sp. 
0r.=9.677-9.935. 

This  element  is  usually  classed  with  Sb;  by  some  writers  among 
the  metals,  by  others  in  the  phosphorus  group.  We  are  led  to  class 
Bi  in  our  fourth  class,  and  in  a  group  alone,  because:  (1)  while  the 
so-called  salts  of  Sb  are  not  salts  of  the  element,  but  of  the  radical 
(SbO)',  antimonyl,  Bi  enters  into  saline  combination,  not  only  in  the 
radical  bismuthyl  (BiO)',  but  also  as  an  element;  (2)  while  the  com- 
pounds of  the  elements  of  the  N  group  in  which  those  elements  are 
quinquivalent  are,  as  a  rule,  more  stable  than  those  in  which  they  arc 
trivalent,  Bi  is  trivalent  in  all  its  known  compounds  except  one. 
which  is  very  unstable,  in  which  it  is  quinquivalent;  (3)  the  hydrates 
of  the  N  group  are  strongly  acid,  and  their  corresponding  salts  n  te- 
stable and  well  defined ;  but  those  hydrates  of  Bi  which  are  acid  are 
but  feebly  so,  and  the  bismuthates  are  unstable ;  (4)  no  compound  of 
Bi  and  H  is  known. 

Occurrence. — Occurs  principally  free,  also  as  Bi203  and  Bi,S3. 

Properties. — Crystallizes  in  brilliant,  metallic  rhombohedra ;  hard 
and  brittle. 

It  is  only  superficially  oxidized  in  cold  air.  Heated  to  redness  in 
air,  it  becomes  coated  with  a  yellow  film  of  oxide.  In  H20,  containing 
C02,  it  forms  a  crystalline  subcarbonate.  It  combines  directly  with 


BISMUTH  143 

Cl,  Br  and  I.     It  dissolves  in  hot  H2S04  as  sulphate,  and  in  HN03 
as  nitrate. 

It  is  usually  contaminated  with  As,  from  which  it  is  best  purified 
by  heating  to  redness  a  mixture  of  powdered  bismuth,  potassium 
carbonate,  soap  and  charcoal,  under  a  layer  of  charcoal.  After  an 
hour  the  mass  is  cooled;  the  button  is  separated  and  fused  until  its 
surface  begins  to  be  coated  with  a  yellowish  brown  oxide. 

Oxides. — Four  oxides  are  known :  Bi202,  Bi203,  Bi204,  and  Bi205. 

Bismuth  Trioxide — Bismuthous  oxide — Bi203— 464 — is  formed  by 
heating  Bi,  or  its  nitrate,  carbonate  or  hydrate.  It  is  a  pale  yellow, 
insoluble  powder;  sp.  gr.  8.2;  fuses  at  a  red  heat;  soluble  in  HC1, 
HN03  and  H,S04  and  in  fused  potash.  Magma  bismuthi  (U.  S.  P.) 
—bismuth  magma — milk  of  bismuth — contains  about  6  per  cent,  of 
Bi203. 

Hydrates. — Bismuth  forms  at  least  four  hydrates. 

Bismuthous  Hydroxide — Bi(OH)3 — 259 — is  formed,  as  a  white 
precipitate,  when  potash  or  ammonium  hydroxide  is  added  to  a  cold 
solution  of  a  Bi  salt.  When  dried  it  loses  H20,  and  is  converted  into 
Bismuthyl  hydroxide  (BiO)OH. 

Bismuth  Trichloride — Bismuthous  chloride — BiCl3 — 314.5 — is 
formed  by  heating  Bi  in  Cl ;  by  distilling  a  mixture  of  Bi  and  mer- 
curic chloride;  or  by  distilling  a  solution  of  Bi  in  aqua  regia.  It  is 
a  fusible,  volatile,  deliquescent  solid ;  soluble  in  dilute  HC1.  On 
contact  with  H20  it  is  decomposed  with  formation  of  bismuthyl 
chloride,  (BiO)Cl,  or  pearl  white. 

Bismuth  Nitrate— Bi(N03)3-f5  Aq— 394+90— obtained  by  dis- 
solving Bi  in  HN03.  It  crystallizes  in  large,  colorless  prisms;  at 
150°,  or  by  contact  with  H2O,  it  is  converted  into  bismuthyl  nitrate; 
at  260°  into  Bi2O3. 

Bismuthyl  Nitrate — Trinitrate  or  subnitrate  of  bismuth — Flake 
white— Bismuthi  subnitras— (U.  S.  P.)  —  (BiO)N03.H20— 304— is 
formed  by  decomposing  a  solution  of  Bi(N03)3  with  a  large  quantity 
of  H20.  It  is  a  white,  heavy,  faintly  acid  powder;  soluble  to  a 
slight  extent  in  H20  when  freshly  precipitated,  the  solution  depositing 
it  again  on  standing.  It  is  decomposed  by  pure  H20,  but  not  by  H20 
containing  %oo  ammonium  nitrate.  It  usually  contains  1  Aq,  which 
it  loses  at  100°.  Bismuth  subnitrate,  as  well  as  the  subcarbonate, 
is  liable  to  contamination  with  arsenic,  which  accompanies  bismuth 
in  its  ores. 

Bismuthyl  Carbonate — Bismuth  subcarbonate — Bismuthi  sub- 
carbonas  (U.  S.  P.)  — (BiO)2C03.H20— 526— is  a  white  or  yellowish, 
timorphous  powder,  formed  when  a  solution  of  an  alkaline  carbonate 
is  added  to  a  solution  of  Bi(N03)3.  It  is  odorless,  tasteless,  and  in- 
soluble in  H20  and  in  alcohol. 

When    heated    to    100°,    it    loses    H20,    and    is    converted    into 


144 


TEXT-BOOK   OF   CHEMISTRY 


(BiO)2C03.    At  a  higher  temperature  it  is  further  decomposed  into 
Bi203  and  C02. 

The  relation  of  the  salts  of  bismuth  to  the  bismuthyl  salts,  may  be 
seen  in  the  following  table: 


BISMUTH 

BISMUTHYL 

Chloride    

BiCl3 

(BiO)Cl 

Bromide  

BiBr3 

(BiO)Br 

Nitrate 

BifNO,), 

(BiO)NOa 

Sulphate   

(Bi),(S(X)» 

(BiO)2SO4 

Carbonate    

(Bi)2(C03)8 

(BiO)2CO8 

Analytical  Characters. —  (1)  Water:  white  ppt.,  even  in  presence 
of  tartaric  acid,  but  not  of  HN03,  HC1,  or  H2S04.  (2)  Hydrogen 
sulphide,  black  ppt.,  insoluble  in  dilute  acids  and  in  alkaline  sul- 
phides. (3)  Ammonium  sulphydrate:  black  ppt.,  insoluble  in  excess. 
(4)  Potash,  soda,  or  ammonia :  white  ppt.,  insoluble  in  excess,  and  in 
tartaric  acid;  turns  yellow  when  the  liquid  is  boiled.  (5)  Potassium 
f errocyanide :  yellowish  ppt.,  insoluble  in  HC1.  (6)  Potassium  ferri- 
cyanide:  yellowish  ppt.,  soluble  in  HC1.  (7)  Infusion  of  galls: 
orange  ppt.  (8)  Potassium  iodide:  brown  ppt.,  soluble  in  excess. 
(9)  Reacts  with  Reinsch's  test  (q.  v.),  but  gives  no  sublimate  in  the 
glass  tube. 

Action  on  the  Economy. — Although  the  medicinal  compounds  of  bismuth 
are  probably  poisonous,  if  taken  in  sufficient  quantity,  the  ill  effects  ascribed 
to  them  are  in  most,  if  not  all  cases,  referable  to  contamination  with  arsenic. 
Symptoms  of  arsenical  poisoning  have  been  frequently  observed  when  the  sub- 
nitrate  has  been  taken  internally,  and  also  when  it  has  been  used  as  a  cosmetic. 
Bismuth  subnitrate  is  frequently  administered  by  physicians  in  cases  of  arsenical 
poisoning,  not  recognized  as  such  during  life. 

When  preparations  of  bismuth  are  administered,  the  alvine  discharges  con- 
tain bismuth  sulphide,  as  a  dark  brown  powder. 


VI.    TIN  GROUP. 

TITANIUM— ZIRCONIUM— TIN 

Ti  and  Sn  are  bivalent  in  one  series  of  compounds,  SnCl,,  and 
quadrivalent  in  another,  SnCl4.  Zr,  so  far  as  known,  is  always 
quadrivalent.  Each  of  these  elements  forms  an  acid  (or  salts  corre- 
sponding to  one)  of  the  composition  of  H2M03,  and  a  series  of  oxy- 
salts  of  the  composition  of  M[V(N03)4. 


TITANIUM   AND   ZIRCONIUM  145 

TITANIUM. 
Symbol  =  Ti — Atomic  weight  =  48 — (International  =  48.1)  —  Sp. 

Occurs  in  clays  and  iron  ores,  and  as  TiO,  in  several  minerals. 
Titanic  anhydride,  Ti02,  is  a  white,  insoluble,  infusible  powder,  used 
in  the  manufacture  of  artificial  teeth ;  dissolves  in  fused  KOH, .  as 
potassium  titanate.  Titanium  combines  readily  with  N,  which  it 
absorbs  from  air  when  heated.  When  NH3  is  passed  over  red-hot 
Ti02,  it  is  decomposed  with  formation  of  the  violet  nitride,  TiN2. 
Another  compound  of  Ti  and  N  forms  hard,  copper-colored,  cubical 
crystals. 

ZIRCONIUM. 

Symbol  =  Zr — Atomic  weight  =  90 — (International  =  90.6) — Sp. 

Occurs  in  zircon  and  hyacinth.  Its  oxide,  zirconia,  Zr02,  is  a 
white  powder,  insoluble  in  KOH.  Being  infusible,  and  not  altered 
by  exposure  to  air,  it  is  used  in  pencils  to  replace  lime  in  the  calcium 
light. 

TIN. 

Symbol=Sn  (Stannum) — Atomic  weight =118. 5 — (International 
=118.7)— Molecular  w eight =237.— Sp.  gr.=7. 285-7. 293. 

Tin  is  bivalent  in  one  series  of  compounds,  SnCl2;  and  quadri- 
valent in  another,  SnCl4. 

Occurrence. — As  tinstone  (Sn02)  or  cassiterite,  and  in  stream 
tin. 

Preparation. — The  commercial  metal  is  prepared  by  roasting  the 
ore,  extracting  with  H20,  reducing  the  residue  by  heating  with  char- 
coal, and  refining. 

Pure  tin  is  obtained  by  dissolving  the  metal  in  HC1;  filtering; 
evaporating ;  dissolving  the  residue  in  H20 :  decomposing  with  am- 
monium carbonate;  and  reducing  the  oxide  with  charcoal. 

Properties. — A  soft,  malleable,  bluish  white  metal;  but  slightly 
tenacious;  emits  a  peculiar  sound,  the  tin-cry,  when  bent.  A  good 
conductor  of  heat  and  electricity.  Air  affects  it  but  little,  except 
when  it  is  heated ;  more  rapidly  if  Sn  is  alloyed  with  Pb.  It  oxidizes 
slowly  in  H20 ;  more  rapidly  in  the  presence  of  sodium  chloride.  Its 
presence  with  Pb  accelerates  the  action  of  H20  upon  the  latter.  It 
dissolves  in  HC1  as  SnCL.  In  presence  of  a  small  quantity  of  H20, 
HN03  converts  it  into  metastannic  acid.  Alkaline  solutions  dissolve 
it  as  metastannates.  It  combines  directly  with  Cl,  Br,  I,  S,  P  and  As. 


146  TEXT-BOOK   OF   CHEMISTRY 

Tin  plates  are  thin  sheets  of  Fe,  coated  with  Sn.  Tin  foil  con- 
sists of  thin  laminae  of  Sn,  frequently  alloyed  with  Pb.  Copper  and 
iron  vessels  are  tinned  after  brightening,  by  contact  with  molten  Sn. 
Pewter,  bronze,  bell  metal,  gun  metal,  britannia  metal,  speculum 
metal,  type  metal,  solder,  and  fusible  metal,  contain  Sn. 

Oxides. — Stannous  Oxide — SnO — 134.5 — obtained  by  heating  the 
hydroxide  or  oxalate  without  contact  of  air.  It  is  a  white,  amorphous 
powder,  soluble  in  acids,  and  in  hot,  concentrated  solution  of  potash. 
It  absorbs  0  readily. 

Stannic  Oxide — Sn02 — 150.5 — occurs  native  as  tinstone  or 
cassiterite,  and  is  formed  when  Sn  or  SnO  is  heated  in  air.  It  is 
used  as  a  polishing  material,  under  the  name  of  putty  powder. 

Hydrates. — Stannous  Hydroxide— Sn  ( OH )  2 — 152.5— is  a  white  precipitate, 
formed  by  alkaline  hydroxides  and  carbonates  in  solution  of  SnCl2. 

Stannic  Acid — H2SnO3 — 168.5 — is  formed  by  the  action  of  alkaline  hy- 
droxides on  solutions  of  SnCl4.  It  dissolves  in  solutions  of  the  alkaline  hy- 
droxides, forming  stannates. 

Metastannic  Acid — H2Sn5Ou — 770.5 — is  a  white,  insoluble  powder,  formed 
by  acting  on  Sn  with  HNO3. 

Chlorides.— Stannous  Chloride— Tin  crystals.— SnCl2+2  Aq— 189.5+ 36— is 
obtained  by  dissolving  Sn  in  HC1.  It  crystallizes  in  colorless  prisms;  soluble  in 
a  small  quantity  of  H2O;  decomposed  by  a  large  quantity,  unless  in  the  pres- 
ence of  free  HC1,  with  formation  of  an  oxychloride.  Loses  its  Aq  at  100°. 
In  air  it  is  transformed  into  stannic  chloride  and  oxychloride.  Oxidizing  and 
chlorinating  agents  convert  it  into  SnCl4.  It  is  a  strong  reducing  agent. 

Stannic  Chloride — Bichloride — SnCl4 — 260.5 — is  formed  by  acting  on  Sn 
or  SnCl2  with  Cl,  or  by  heating  Sn  in  aqua  regia.  It  is  a  fuming,  yellowish 
liquid;  sp.  gr.  2.28;  boils  at  120°. 

Analytical  Characters. — STANNOUS. — (1)  Potash,  or  soda:  white 
ppt. ;  soluble  in  excess;  the  solution  deposits  Sn  when  boiled. 
(2)  Ammonium  hydroxide:  white  ppt;  insoluble  in  excess;  turns 
olive-brown  when  the  liquid  is  boiled.  (3)  Hydrogen  sulphide:  dark 
brown  ppt.;  soluble  in  KOH,  alkaline  sulphides,  and  hot  H20.  (4) 
Mercuric  chloride:  white  ppt.,  turning  gray  and  black.  (5)  Auric 
chloride:  purple  or  brown  ppt.,  in  presence  of  small  quantities  of 
HN03.  (6)  Zinc:  deposit  of  Sn. 

STANNIC. —  (1)  Potash,  or  ammonia:  white  ppt.;  soluble  in  excess. 
(2)  Hydrogen  sulphide:  yellow  ppt.;  soluble  in  alkalies,  alkaline 
sulphides,  and  hot  HC1.  (3)  Sodium  hyposulphite:  yellow  ppt.,  when 
heated. 


PLATINUM  147 

VII.  PLATINUM  GROUP. 
PALLADIUM.     PLATINUM. 

VIII.  RHODIUM  GROUP. 
RHODIUM.     RUTHENIUM.     IRIDIUM. 

The  elements  of  these  two  groups,  together  with  osmium,  are 
usually  classed  as  "metals  of  the  platinum  ores."  They  all  form 
hydrates  (or  salts  representing  them)  having  acid  properties.  Os- 
mium has  been  removed,  because  the  relations  existing  between  its 
compounds,  and  those  of  molybdenum  and  tungsten,  are  much  closer 
than  those  which  they  exhibit  to  the  compounds  of  these  groups. 
The  separation  of  the  remaining  platinum  metals  into  two  groups  is 
based  upon  resemblances  in  the  composition  of  their  compounds,  as 
shown  in  the  following  tables: 

CHLOBIDES. 

PdCl2 PtCl2  RhCl2 RuCl2 ? 

PdCl4 PtCl4  RuCl4 IrCl4 

Rh2Cl6 Ru2Cla Ir2Cl6 

OXIDES. 

PdO PtO  RhO  RuO  IrO 

— —  Rh2O3 Ru2O3 Ir208 

Pd02 Pt02  Rh02 Ru02 ; . .  .Ir02 

— Rh03 Ru03 Ir03 

Ru04 - 

PLATINUM. 

Symbol=Pi — Atomic  weight=195 — (International=195.2) — Mo- 
lecular weight=390—Sp.  gr. =21.1-21.5. 

Occurrence. — Free  and  alloyed  with  Os,  Ir,  Pd,  Rh,  Ru,  Fe,  Pb, 
Au,  Ag  and  Cu. 

Properties. — The  compact  metal  has  a  silvery  luster;  softens  at 
a  white  heat ;  may  be  welded ;  fuses  with  difficulty ;  highly  malleable, 
ductile  and  tenacious.  Spongy  platinum  is  a  grayish,  porous  mass, 
formed  by  heating  the  double  chloride  of  Pt  and  NH4.  Platinum 
black  is  a  black  powder,  formed  by  dissolving  PtCl2  in  solution  of 
potash,  and  heating  with  alcohol.  Both  platinum  black  and  platinum 
sponge  are  capable  of  condensing  large  quantities  of  gas,  and  act  as 
indirect  oxidants. 


148  TEXT-BOOK   OF   CHEMISTRY 

Platinum  is  not  oxidized  by  air  or  0 ;  it  combines  directly  with  Cl, 
P,  As,  Si,  S,  and  C ;  is  not  attacked  by  acids,  except  aqua  regia,  in 
which  it  dissolves.  It  forms  fusible  alloys  when  heated  with  metals 
or  reducible  metallic  oxides.  It  is  attacked  by  mixtures  liberating 
Cl,  and  by  contact  with  heated  phosphates,  silicates,  hydroxides, 
nitrates,  or  carbonates  of  the  alkaline  metals. 

Platinic  Chloride — Tetrachloride  of  platinum — PtCl4 — 337— 
When  Pt  is  dissolved  in  aqua  regia  and  the  solution  is  evaporated, 
red,  deliquescent  crystals  of  hydrochloroplatinic  acid,  H2PtClc,  are 
obtained.  These,  when  heated  in  chlorine,  yield  yellow,  non-deli- 
quescent crystals  of  platinic  chloride,  PtCl4.  Hydrochloroplatinic 
acid  is  a  strong  dibasic  acid,  the  platinum  being  in  the  anion,  which 
forms  crystalline  chloroplatinates  with  the  alkaline  metals,  NH4,  and 
a  great  number  of  nitrogenous  organic  bases.  The  formation  of  the 
K  and  NH4  salts  is  utilized  to  test  for  those  cations,  and  the  forma- 
tion of  the  organic  compounds  is  resorted  to  for  the  identification 
and  analysis  of  these  bases. 


CLASS  V-— BASYLOUS  ELEMENTS. 

Elements  whose  Oxides  unite  with  Water  to  form  Bases;  never  to  form 
Acids.     Which  form   Oxysalts. 

The  elements  of  this  class  are  essentially  basic  and  electropositive. 
In  solutions  of  their  compounds  they  never  occur  in  an  anion,  simple 
or  compound,  but  always  constitute  simple  cations. 

I.     SODIUM  GROUP. 

Alkali  Metals. 
LITHIUM— SODIUM— POTASSIUM— RUBIDIUM— CESIUM— SILVER. 

Each  of  the  elements  of  this  group  forms  a  single  chloride,  M'Cl, 
and  one  or  more  oxides,  the  most  stable  of  which  has  the  composition 
M'20.  They  are,  therefore,  univalent.  Their  hydroxides,  M'OH,  are 
more  or  less  alkaline  and  have  markedly  basic  characters.  Silver 
resembles  the  other  members  of  the  group  in  chemical  properties, 
although  it  does  not  in  physical  characters. 

The  name  "alkali,"  first  applied  to  "potash"  from  wood  ashes 
(p.  160)  is  now  used  to  designate  substances  which- are  strongly  basic, 
are  alkaline  in  reaction,  and  saponify  fats.  The  caustic  alkalies  are 
the  hydroxides  of  K  and  Na,  the  carbonated  alkalies  are  their  car- 
bonates. Volatile  alkali  is  ammonium  hydroxide  or  carbonate. 

LITHIUM. 

Symbol=lA— Atomic  weight— 1 — (International^.^) — Molecu- 
lar weight=U—Sp.  #r.=0.589. 

Occurrence. — Widely  distributed  in  small  quantity,!;  in  many  min- 
erals and  mineral  waters;  in  the  ash  of  tobacco  and  other  plants;  in 
the  milk  and  blood. 

Properties. — A  silver-white,  ductile,  volatile  metal;  the  lightest 
of  the  solid  elements;  burns  in  air  with  a  crimson  flame;  decomposes 
H20  at  ordinary  temperatures,  without  igniting. 

Lithium  Chloride. — LiCl — 42.5 — crystallizes  in  deliquescent,  regu- 
lar octahedra ;  very  soluble  in  H20  and  in  alcohol. 

Lithium  Bromide— Lithii  bromidum— (U.  S.  P.)— LiBr— 87 — is 
formed  by  decomposing  lithium  sulphate  with  potassium  bromide; 
oi'  by  saturating  a  solution  of  HBr  with  lithium  carbonate.  It  crystal- 
lizes in  very  deliquescent,  soluble  needles. 

149 


150 


TEXT-BOOK   OP   CHEMISTRY 


Lithium  Carbonate — Lithii  carbonas  (U.  S.  P.) — Li2C03 — 74— 
is  a  white,  sparingly  soluble,  alkaline,  amorphous  powder.  With 
uric  acid  it  forms  lithium  urate,  which  is  the  most  soluble  of  the 
urates  of  this  class,  and  is  therefore  given  to  patients  suffering  from 
"the  uric  acid  diathesis." 


Red.    Orange.    Yellow.     Green. 


Blue. 


Cyan- 
blue.    Violet. 


•Tl. 


In. 


Ga 


11 


FIG.  16. — 1,  Solar  spectrum;  10  and  11,  Absorption  spectra. 

Lithium  bicarbonate — LiHC03 — 68 — is  the  salt  which  is  present 
in  lithia  water.  It  is  derived  from  the  carbonate : 

Li2C03+C02+H20=2LiHC08 

Analytical  Characters. — (1)  Ammonium  carbonate:  white  ppt.  in 
concentrated  solutions;  not  in  dilute  solutions,  or  in  presence  of 
ammoniacal  salts.  (2)  Sodium  phosphate:  white  ppt.  in  neutral  or 
alkaline  solution ;  soluble  in  acids  and  in  solutions  of  ammoniacal 


SODIUM  151 

salts.     (3)  It  colors  the  Bunsen  flame  red;  and  exhibits  a  spectrum 
of  two^ines—  A  =6705  and  6102  (Fig.  16,  No.  4,  p.  150). 

SODIUM. 

Symbol=~Na  (Natrium) — Atomic  weig~ht=23 — (International^ 
23.00)— Molecular  weight— 46— Sp.  gr.=0.972. 

Occurrence. — As  chloride,  very  abundantly  and  widely  dis- 
tributed; also  as  carbonate,  nitrate,  sulphate,  borate,  etc. 

Preparation. — By  heating  a  mixture  of  dry  sodium  carbonate, 
chalk,  and  charcoal  to  whiteness  in  iron  retorts: 

Na2C03+2C=3CO+Na2 

It  is  now  manufactured  by  the  electrolysis  of  fused  NaOH. 

Properties. — A  silver-white  metal,  rapidly  tarnished,  and  coated 
with  a  yellow  film  in  air.  Waxy  at  ordinary  temperatures;  volatile 
at  a  white  heat,  forming  a  colorless  vapor,  which  burns  in  air  with  a 
yellow  flame. 

It  oxidizes  in  air,  and  is  usually  preserved  under  naphtha.  It 
burns  with  a  yellow  flame.  It  combines  directly  with  Cl,  Br,  I,  S,  P, 
As,  Pb  and  Sn.  It  decomposes  water  with  evolution  of  hydrogen: 
Na2+2H20=2NaOH-f  H2.  Because  of  this  and  other  similar  re- 
actions, metallic  sodium,  either  as  such  or  in  the  diluted  form  of 
sodium  amalgam,  is  largely  used  to  effect  reductions. 

Oxides. — Two  oxides  are  known:  Sodium  monoxide — Na20 — a 
grayish  white  mass;  formed  when  Na  is  burnt  in  dry  air,  or  by  the 
action  of  Na  on  NaOH.  Sodium  dioxide — Na202 — a  white  solid, 
formed  when  Na  is  heated  in  dry  air  to  200°.  Sodium  dioxide,  or 
peroxide,  is  now  manufactured  by  oxidizing  the  fused  metal  in  dry 
air  or  oxygen,  and  is  used  as  a  bleaching  and  oxidizing  agent.  It  is 
a  yellowish  white,  amorphous,  very  hygroscopic  powder.  If  the 
temperature  is  kept  low  it  dissolves  in  dilute  acids,  forming  a  strong 
solution  of  hydrogen  dioxide:  Na202+2HCl=2NaCl+H202.  With 
water  it  produces  a  great  elevation  of  temperature  and  liberates 
nascent  oxygen:  2Na202+2H20=4NaOH4-02.  With  magnesium 
sulphate  it  forms  magnesium  dioxide,  a  non-alkaline  oxidant :  Na202+ 
MgS04=Na2S04+Mg02. 

Sodium  Hydroxide — Sodium  hydrate — Caustic  Soda — Sodium 
Hydroxidum  (U.  S.  P. )  —NaOH— 40— is  formed:  (1)  When  H20  is 
decomposed  by  Na;  (2)  by  decomposing  sodium  carbonate  by  calcium 
hydroxide:  Na2C03+Ca(OH)2=C03Ca+2NaOH  (soda  by  lime); 
(3)  in  the  same  manner  as  in  (2),  using  barium  hydroxide  in  place 
of  lime  (soda  by  baryta).  It  frequently  contains  considerable  quan- 
tities of  As. 

It  is  an  opaque,  white,  fibrous,  brittle  solid;  fusible  below  red- 
ness; sp>  £r.  2.00;  very  soluble  in  H20,  forming  strongly  alkaline 


152  TEXT-BOOK   OF   CHEMISTRY 


and  caustic  solutions,  soda  lye  and  liquor  sodii  hydroxidi,  U.  8.  P., 
(containing  not  less  than  4.5  per  cent,  of  NaOH).  When  exposed  to 
air,  solid  or'  in  solution,  it  absorbs  ILO  and  CO,,  and  is  converted 
into  carbonate.  Its  solutions  attack  glass. 

Sodium  Chloride — Common  salt — Sea  salt — Table  salt — Sodii 
chloridum  (U.  S.  P.)— NaCl — 58.5 — occurs  very  abundantly  in 
nature,  deposited  in  the  solid" form  as  rock  salt;  in  solution  in  all 
natural  waters,  especially  in  sea  and  mineral  spring  waters ;  in  sus- 
pension in  the  atmosphere;  and  as  a  constituent  of  almost  all  animal 
and  vegetable  tissues  and  fluids.  It  is  formed  in  an  infinite  variety 
of  chemical  reactions.  It  is  obtained  from  rock  salt,  or  from  the 
waters  of  the  sea,  or  of  saline  springs;  and  is  the  source  from  which 
all  the  Na  compounds  are  usually  obtained,  directly  or  indirectly. 

It  crystallizes  in  anhydrous,  white  cubes,  or  octahedra  ;  xp,  gr. 
2.078;  fuses  at  a  red  heat,  and  crystallizes  on  cooling;  sensibly  vola- 
tile at  a  white  heat;  quite  soluble  in  H,0,  the  solubility  varying  but 
slightly  with  the  variations  of  temperature.  Dilute  solutions  yield 
almost  pure  ice  on  freezing.  It  is  precipitated  from  concentrated 
solutions  by  HC1.  It  is  insoluble  in  absolute  alcohol;  sparingly  sol- 
uble in  dilute  spirit.  It  is  decomposed  by  H.,S04  with  formation  of 
HC1  and  sodium  sulphate:  2NaCl+ H2S04=2HCl+Na,S04. 

Physiological  salt  solution  (Liquor  sodii  chloridi  physiologic  us, 
U.  S.  P.)  contains  8.5  gms.  of  NaCl  in  a  liter  of  distilled  water. 

Sodium  Bromide— Sodii  bromidum  (U.  S.  P.)— NaBr— 103— is 
formed  by  dissolving  Br  in  solution  of  NaOH  to  saturation ;.  evapo- 
rating; calcining  at  dull  redness;  redissolving,  filtering,  and  crystal- 
lizing. It  crystallizes  in  anhydrous  cubes;  quite  soluble  in  ELO, 
soluble  in  alcohol. 

Sodium  Iodide — Sodii  iodidum  (U.  S.  P.) — :NaI — 150 — is  pre- 
pared by  heating  together  H,0,  Fe,  and  I  in  fine  powder ;  filtering ; 
adding  an  equivalent  quantity  of  sodium  sulphate,  and  some  slaked 
lime,  boiling,  decanting  and  evaporating.  Crystallizes  in  anhydrous 
cubes ;  very  soluble  in  H20 ;  soluble  in  alcohol. 

Sodium  Nitrate — Cubic  or  Chili  saltpeter — NaN03 — 85 — occurs 
in  natural  deposits  in  Chili  and  Peru.  It  crystallizes  in  anhydrous, 
deliquescent  rhombohedra;  cooling  and  somewhat  bitter  in  taste; 
fuses  at  310°;  very  soluble  in  H20.  Heated  with  H2SO4,  it  is  de- 
composed, yielding  HN03  and  hydrosodic  sulphate:  H.,S04-}-NaN03= 
HNaS04-f  UNO,.  This  reaction  is  that  used  for  obtaining  HN< )  . 

Sulphates. — Monosodic  Sulphate — Ht/drosodic  sulphate — Add 
sodium  sulphate — Bisulphatc — HNaS04— 120 — crystallizes  in  long, 
four-sided  prisms;  is  unstable  and  decomposed  by  air,  H20  or  alcohol, 
into  H2S04  and  Xa.,S04.  Heated  to  dull  redness  it  is  converted  into 
sodium  pyrosulphate,  Na2So07,  corresponding  to  Nordhausen  sul- 
phuric acid. 

Disodic  Sulphate — Sodium  sulphate — Neutral  sodium  sulphate— 


SODIUM  153 

Glauber's  salt— Sodii  sulphas  (U.  S.  P.)—  Na2S04+Aq— 142+18— 
occurs~in  nature  in  solid  deposits,  and  in  solution  in  natural  waters; 
It  is  obtained  as  a  secondary  product. in  the  manufacture  of  HCI,  by 
the  action  of  H2S04  on  NaCl,  the  decomposition  occurring  according 
to  the  equation?  2NaCl+H2S04=Na2S04+2HCl,  if  the  temperature 
is  raised  sufficiently.  At  lower  temperatures,  the  monosodic 
salt  is  produced,  with  only  half  the  yield  of  HCI:  NaCl+H9SO4= 
NaHS04+HCl. 

It  crystallizes  with  7  Aq,  from  saturated  or  supersaturated  solu- 
tions at  5°;  or,  more  usually,  with  10  Aq.  As  usually  met  with  it 
is  in  large,  colorless,  oblique,  rhombic  prisms  with  10  Aq;  which 
effloresce  in  air,  and  gradually  lose  all  their  Aq.  It  fuses  at  33°  in 
its  Aq,  which  it  gradaully  loses.  If  fused  at  33°  and  allowed  to 
cool,  it  remains  liquid  in  supersaturated  solution,  from  which  it  is 
deposited,  the  entire  mass  becoming  solid,  on  contact  with  a  small 
particle  of  solid  matter.  It  dissolves  in  HCI  with  considerable 
diminution  of  temperature. 

Sodium  Sulphite— Na2S03+7  Aq— 126+126— is  formed  by  pass- 
ing S02  over  crystallized  Na2C03.  It  crystallizes  in  efflorescent, 
oblique  prisms;  quite  soluble  in  H20,  forming  an  alkaline  solution. 
It  acts  as  a  reducing  agent. 

Sodium  Thiosulphate — Sodium  hyposulphite — Sodii  thiosulphas 
(U.  S.  P.)— Na2S203+5  Aq— 158+90— is  obtained  by  dissolving  S  in 
hot  concentrated  solution  of  Na2S03,  and  crystallizing. 

It  forms  large,  colorless,  efflorescent  prisms;  fuses  at  45°; -very 
soluble  in  H2O,  insoluble  in  alcohol.  Its  solutions  precipitate  alumina 
from  solutions  of  Al  salts,  without  precipitating  Fe  or  Mn;  they 
dissolve  many  compounds  insoluble  in  H20 ;  cuprous  hydroxide, 
iodides  of  Pb,  Ag  and  Hg,  sulphides  of  Ca  and  Pb.  It  is  used  in 
photography  as  a  fixing  bath,  and  is  called  "hypo";  it  acts  as  a 
disinfectant  and  antiseptic;  it  is  also  employed  in  bleaching,  to 
remove  the  chlorine.  H2S04  decomposes  Na2S203  according  to  the 
equation : 

Na2S203+H2S04=Na2S04+S02+S+H20 

and  most  other  acids  behave  similarly.  Oxalic,  and  a  few  otker 
acids,  decompose  the  thiosulphate  with  formation  of  H2S  as  well  as 
S02  and  S. 

Silicates. — Quite  a  number  of  silicates  of  Na  are  known.  If  silica  and 
Na2C03  are  fused  together,  the  residue  extracted  with  H;,0,  and  the  solution 
evaporated,  a  transparent,  glass-like  mass,  soluble  in  warm  water,  remains; 
this  is  soluble  glass  or  water  glass.  Exposed  to  air  in  contact  with  stone,  it 
becomes  insoluble,  and  forms  an  impermeable  coating. 

Phosphates. — Trisodic  Phosphate — Basic  sodium  phosphate— 
Na3P04+12  Aq— 164+216— is  obtained  by  adding  NaOH  to  disodic 
phosphate  solution,  and  crystallizing.  It  forms  six-sided  prisms; 


154  TEXT-BOOK   OF   CHEMISTRY 

quite  soluble  in  H20.     Its  solution  is  alkaline,  and,  on  exposure  to 
air,  absorbs  C02,  with  formation  of  HNa2P04  and  Na2C03. 

Disodic  Phosphate — Sodium  phosphate — Hydro-disodic  phosphate 
— Neutral  sodium  phosphate — Phosphate  of  soda — Sodii  phosphas 
(U.  S.  P.)—  HNa2P04+12  Aq— 142+216— is  obtained  by  converting 
tricalcic  phosphate  into  monocalcic  phosphate,  and  decomposing  that 
salt  with  sodium  carbonate: 

Ca(P04H2)2+2Na2C03=CaC03+H204-C02+2HNa2P04. 

Below  30°  it  crystallizes  in  oblique  rhombic  prisms,  with  12  Aq; 
at  33°  it  crystallizes  with  7  Aq.  The  salt  with  12  Aq  effloresces  in 
air,  and  parts  with  5  Aq ;  and  is  very  soluble  in  H20.  The  salt  with 
7  Aq  is  not  efflorescent,  and  less  soluble  in  H20.  Its  solutions  are 
faintly  alkaline. 

Monosodic  Phosphate — Acid  sodium  phosphate — H2NaP04+ 
Aq — 120-|-18 — crystallizes  in  rhombic  prisms ;  forming  acid  solutions. 
At  100  °  it  loses  Aq ;  at  200  °  it  is  converted  into  acid  pyrophosphate, 
Na2H2P207;  and  at  204°  into  the  metaphosphate,  NaP03. 

Sodium  Arsenites. — The  disodic  arsenite,  Na2HAs03,  is  obtained  as  a 
viscous  mass  by  fusing  together  1  molecule  of  As2O3  and  2  molecules  of  Na2CO3 
without  contact  of  air.  The  monosodic  arsenite,  NaH2AsO3,  is  formed  when 
an  aqueous  solution  of  Na2C03  is  boiled  with  As2O3.  By  prolonged  boiling 
this  is  converted  into  the  pyroarsenite,  Na2H2As2O3,  and  this  into  the  metarsenite, 
NaAs02,  by  progressive  loss  of  water.  Sodium  arsenites  exist  in  embalming 
liquids  and  are  used  in  dyeing. 

Sodium  Arsenates. — The  three  arsenates,  NaH2As04,  Na2HAs04  and 
NaaAsO4  corresponding  to  the  phosphates,  are  known,  and  are  used  in  dyeing 
processes. 

Disodic  Tetraborate — Sodium  pyroborate — Borate  of  sodium— 
Borax— Sodii  boras  (U.  S.  P.)—  Na2B407+10  Aq— 202+180— is 
prepared  by  boiling  boric  acid  with  Na2C03  and  crystallizing: 

4H3B03+Na2C03=C02+6H20+Na2B407 

It  crystallizes  in  hexagonal  prisms  with  10  Aq;  permanent  in 
moist  air,  but  efflorescent  in  dry  air;  or  in  regular  octahedra  with 
5  Aq,  permanent  in  dry  air.  Either  form,  when  heated,  fuses  in  its 
Aq,  swells  considerably;  at  a  red  heat  becomes  anhydrous;  and,  on 
cooling,  leaves  a  transparent,  glass-like  mass.  When  fused  it  is 
capable  of  dissolving  many  metallic  oxides,  forming  variously  col- 
ored masses,  hence  its  use  as  a  flux  and  in  blow-pipe  analysis. 

Sodium  Hypochlorite — NaCIO — 74.5 — only  known  in  solution— Liquor 
sodae  chlorinatae  (U.  S.  P.)  or  Labarraque's  solution — obtained  by  decom- 
posing a  solution  of  chloride  of  lime  by  Na2C03.  It  is  a  valuable  source  of  Cl, 
and  is  used  as  a  bleaching  and  disinfecting  agent.  The  pharmacopcrial  prepara- 
tion should  contain  not  less  than  2.5  per  cent,  of  available  chlorine. 

Sodium  Chlorate— NaClO3—l  06.5— is  manufactured  industrially  by  treating 
milk  of  lime  with  Cl.  The  solution  of  calcium  chloride  and  chlorate  so  obtained 


SODIUM  155 

is  treated  with  Na2S04,  after  removal  of  part  of  the  CaCl2  by  concentration  and 
cooling  to  12°.  The  NaC103  and  NaCl  formed  are  separated  by  taking  advan- 
tage of  the  greater  solubility  of  the  former.  NaClO3  is  soluble  in  its  own 
weight  of  H20  at  20°. 

Sodium  Permanganate — NaMn04 — 142— prepared  in  the  same  way  as  the 
K  salt  (q.  v.),  which  it  resembles  in  its  properties.  It  enters  into  the  com- 
position of  Condy's  fluid,  and  of  "chlorozone,"  which  contains  NaMnO4  and 
NaClO. 

Sodium    Acetate— Sodii  acetas     (U.    S.    P. )  —  NaC2H302+3Aq— 82+54— 

crystallizes  in  large,  colorless  prisms ;    acid  and  bitter   in  taste ;    quite   soluble 

in  H2O,  soluble  in  alcohol;  loses  its  Aq  in  dry  air,  and  absorbs  it  again  from 

moist  air.    It  may  be  prepared  by  saturating  acetic  acid  with  sodium  carbonate: 

2C2HA+Na2C03=H20+C02+2NaC2H302 

Heated  with  soda  lime,  it  yields  marsh  gas.  The  anhydrous  salt,  heated 
with  H2S04,  yields  glacial  acetic  acid. 

Carbonates.— Three  are  known:  Na2C03,  HNaC03,  and  H2Na4- 
(C03)3. 

Disodic  Carbonate — Sodium  carbonate — Neutral  Carbonate — 
Soda— Sal  soda— Washing  Soda— Soda  crystals— Na2C03+ 10  Aq— 
106+180 — industrially  the  most  important  of  the  Na  compounds,  is 
manufactured  by  Leblanc's  or  Solvay's  processes;  or  from  cryolite, 
a  native  fluoride  of  Na  and  Al. 

Leblanc's  process,  in  its  present  form,  consists  of  three  distinct 
processes:  (1)  The  conversion  of  NaCl  into  the  sulphate,  by  decom- 
position by  H2S04.  (2)  The  conversion  of  the  sulphate  into  car- 
bonate, by  heating  a  mixture  of  the  sulphate  with  calcium  carbonate 
and  charcoal.  The  product  of  this  reaction,  known  as  black  ball  soda, 
is  a  mixture  of  sodium  carbonate  with  charcoal  and  calcium  sulphide 
and  oxide.  (3)  The  purification  of  the  product  obtained  in  (2). 
The  ball  black  is  broken  up,  disintegrated  by  steam,  and  lixiviated. 
The  solution  on  evaporation  yields  the  soda  salt  or  soda  of  commerce. 

Of  late  years  Leblanc's  process  has  been  in  great  part  replaced 
by  Solvay's  method,  or  the  ammonia  process,  which  is  more  eco- 
nomical, and  yields  a  purer  product.  In  this  process  sodium  chloride 
and  ammonium  bicarbonate  react  upon  each  other,  with  production  of 
the  sparingly  soluble  sodium  bicarbonate,  and  the  very  soluble  am- 
monium chloride.  The  sodium  bicarbonate  is  then  simply  collected, 
dried,  and  heated,  when  it  is  decomposed  into  Na2C03,  H20,  and  C02. 
Sodium  carbonate  is  also  made  from  cryolite,  a  double  fluoride  of 
sodium  and  aluminium  found  in  Greenland.  This  is  heated  with 
limestone  when: 

Al2NaaF12+6CaC08=6CaF2+6C02+NaeAl206 

The  sodium  aluminate  is  extracted  with  water  and  the  solution  treated 
with  carbon  dioxide  (obtained  in  the  first  reaction)  when: 

Na6Al206+3H20+3C02=3Na2C03+Al2(OH)6 
The  monohydrated  carbonate,  Sodii  carbonas  monohydratus   (U. 


156  TEXT-BOOK   OF   CHEMISTRY 

S.  P.),  Na2C03-|-H20  is  a  white,  crystalline,  granular  powder.     It 
combines  with  and  dissolves  in  H20  with  elevation  of  temperature. 

The  crystalline  sodium  carbonate,  Na2C03-f-10Aq,  forms  large 
rhombic  crystals,  which  effloresce  rapidly  in  dry  air;  fuse  in  their 
Aq  at  34°;  are  soluble  in  H20,  most  abundantly  at  38°.  The  solu- 
tions are  alkaline  in  reaction. 

Sodium    Bicarbonate — Monosodic    Carbonate — Bicarbonate    of 
,soda — Acid  carbonate   of  soda — Vichy   salt — Sodii   bicarbonas    (U. 
S.   P.) — NaHC03 — 84 — exists  in   solution   in   many   mineral    waters. 
It  is  obtained  by  the  action  of  C02  upon  the  disodic  salt  in  the  pres- 
ence of  H20 ;  or,  as  above  described,  by  the  Solvay  method. 

.  It  crystallizes  in  rectangular  prisms,  anhydrous  and  permanent  in 
dry  air.  In  damp  air  it  gives  off  C02,  and  is  converted  into  the 
sesquicarbonate,  Na4H2(C03)3.  When  heated  it  gives  off  C02  and 
H20,  and  leaves  the  disodic  carbonate.  Quite  soluble  in  water; 
above  70°  the  solution  gives  off  C02.  The  solutions  are  alkaline. 

Analytical  Characters. —  (1)  Hydrofluosilicic  acid:  gelatinous 
ppt.,  if  not  too  dilute.  (2)  Potassium  pyroantimonate,  in  neutral 
solution,  and  in  absence  of  metals  other  than  K  and  Li :  a  white, 
flocculent  ppt.;  becoming  crystalline  on  standing.  (3)  Periodic  acid 
in  excess:  white  ppt.,  in  not  too  dilute  solutions.  (4)  Colors  the 
Bunsen  flame  yellow,  and  shows  a  brilliant  double  line  at  A  =5895 
and  5889  (Fig.  16,  No.  2,  p.  150). 

POTASSIUM. 

Symbol  =  K  (Kalium) — Atomic  weight  =  39 — (International  = 
39.10)— Molecular  weight=7S—Sp.  gr.=0.865. 

Potassium  silicates  are  widely  distributed  in  rocks  and  minerals. 
The  ash  of  plants  contains  about  10  per  cent,  of  potassium  carbonate, 
and  this  was  formerly  the  chief  source  of  the  K  compounds.  Almost 
all  of  these  are  now  derived  from  the  deposits  of  carnallite:  KC1, 
MgCl2+6Aq,  and  allied  minerals  at  Stassfurt  in  Germany. 

It  is  prepared  by  a  process  similar  to  that  followed  in  obtaining 
Na ;  is  a  silver-white  metal ;  brittle  at  0°  ;  waxy  at  15°  ;  fuses  at  62.5 ° ; 
distils  in  green  vapors  at  a  red  heat,  condensing  in  cubic  crystals. 
It  is  also  obtained  by  electrolysis  of  fused  KOH. 

It  is  the  only  metal  which  oxidizes  at  low  temperatures  in  dry  air. 
in  which  it  is  rapidly  coated  with  a  white  layer  of  oxide  or  hydroxide. 
and  frequently  ignites,  burning  with  a  violet  flame.  It  must,  there- 
fore, be  kept  under  naphtha.  It  decomposes  H20,  or  ice,  witli  great 
energy,  the  heat  of  the  reaction  igniting  the  liberated  H.  It  com- 
bines with  Cl  with  incandescence,  and  also  unites  directly  with  S,  P, 
As,  Sb,  and  Sn.  Heated  in  C02  it  is  oxidized,  and  liberates  C. 

Oxides. — Three  are  known :  K20  ;  K202 ;  and  K204. 

Potassium  Hydroxide — Potassium  hydrate — Potash — Potassa — 


POTASSIUM  157 

Caustic:  Potash — Common  caustic — Potassii  hydroxidum  (IT.  S.  P.) 
— KOH — 56 — is  obtained  by  processes  similar  to  those  used  in  manu- 
facturing NaOH.  It  is  purified  by  solution  in  alcohol,  evaporation  and 
fusion  in  a  silver  basin,  and* casting  in  silver  moulds — potash  by 
alcohol;  it  is  then  free  from  KC1  and  K2S04,  but  contains  small 
quantities  of  K2C03,  and  frequently  As. 

It  is  usually  met  with  in  cylindrical  sticks,  hard,  white,  opaque, 
and  brittle.  The  KOH  by  alcohol  has  a  bluish  tinge,  and  a  smoother 
surface  than  the  common ;  sp.  gr.  2.1 ;  fuses  at  dull  redness ;  is  freely 
soluble  in  H20,  forming  a  strongly  alkaline  and  caustic  liquid;  less 
soluble  in  alcohol.  In  air,  solid  or  in  solution,  it  absorbs  H20  and 
C02,  and  is  converted  into  K2C03.  Its  solutions  dissolve  Cl,  Br, 
I,  S,  and  P.  It  decomposes  the  ammoniacal  salts,  with  liberation 
of  NH3;  and  the  salts  of  many  of  the  metals,  with  formation  of 
a  K  salt,  and  a  metallic  hydroxide.  It  dissolves  the  proteins,  and, 
when  heated,  decomposes  them  with  formation  of  leucin,  tyrosin, 
etc.  It  oxidizes  the  carbohydrates  with  formation  of  potassium 
oxalate  and  carbonate.  It  decomposes  the  fats  with  formation  "of 
soft  soaps. 

Solution  of  potassium  hydroxide  (liquor  potassii  hydroxidi, 
U.  S.  P.)  or  liquor  potassce,  is  an  aqueous  solution  containing  not  less 
than  4.5  per  cent  of  KOH. 

Liver  of  Sulphur — Jiepar  sulpliuris — potassa  sulphurata  (U.  S. 
P) — is  a  mixture  of  K2S3  and  K2S203,  and  contains  not  less  than 
12.8  per  cent,  of  sulphur. 

Potassium  Chloride — KC1 — 74.5 — exists  in  nature,  either  pure 
or  mixed  with  other  chlorides;  principally  as  carnallite,  KC1, 
MgCl2+6  Aq.  It  crystallizes  in  anhydrous,  permanent  cubes,  soluble 
in  H20. 

Potassium  Bromide — Potassii  bromidum  (U.  S.  P.) — KBr — 119 
—is  formed  either  by  decomposing  FeBr2  by  K2C03,  or  by  dissolving 
Br  in  solution  of  KOH.  In  the  latter  case  the  bromate  formed  is 
converted  into  KBr,  by  calcination.  It  crystallizes  in  anhydrous 
cubes  or  tables;  has  a  sharp,  salty  taste;  very  soluble  in  H20,  spar- 
ingly so  in  alcohol.  It  is  decomposed  by  Cl  with  liberation  of  Br. 

Potassium  Iodide — Potassii  iodidum  (U.  S.  P.) — KI— 166 — is 
obtained  by  saturating  KOH  solution  with  I,  evaporating,  and  calcin- 
ing the  resulting  mixture  of  iodide  and  iodate  with  charcoal: 

6KOH+3I2=3H20+KI03+5KI 

It  frequently  contains  iodate  and  carbonate.  It  crystallizes  in 
cubes,  transparent  if  pure;  permanent  in  air;  anhydrous;  soluble  in 
H20  and  in  alcohol.  It  is  decomposed  by  Cl,  HN03  and  HN02  with 
liberation  of  I.  It  combines  with  other  iodides  to  form  double  iodides. 
Its  solutions  dissolve  iodine  and  many  metallic  iodides. 

Potassium  Nitrate — Nitre — Saltpeter — Potassii  nitras  (U.  S.  P.) 


158  TEXT-BOOK   OF   CHEMISTRY 

— KN03 — 101 — occurs  in  nature,  and  is  produced  artificially,  as  a 
result  of  the  decomposition  of  nitrogenized  organic  substances.  It  is 
usually  obtained  by  decomposing  native  NaN03  by  boiling  solution 
of  K2C03  or  KC1. 

It  crystallizes  in  six-sided,  rhombic  prisms,  grooved  upon  the 
surface;  soluble  in  H20,  with  depression  of  temperature;  more  sol- 
uble in  H20  containing  NaCl ;  very  sparingly  soluble  in  alcohol ;  fuses 
at  350°  without  decomposition;  gives  off  0,  and  is  converted  into 
nitrite  below  redness;  more  strongly  heated,  it  is  decomposed  into 
N,  0,  and  a  mixture  of  K  oxides.  It  is  a  valuable  oxidant  at  high 
temperatures.  Heated  with  charcoal  it  deflagrates. 

Gunpowder  is  an  intimate  mixture  of  KN03  with  S  and  C,  in  such 
proportion  that  the  KN03  yields  all  the  0  required  for  the  combustion 
of  the  S  and  C. 

Potassium  Hypochlorite — KC10 — 90.5 — is  formed  in  solution  by 
imperfect  saturation  of  a  cooled  solution  of  KOH  with  hypochlorous 
acid.  An  impure  solution  is  used  in  bleaching,  and  is  known  as 
Javelle  water,  which  is  the  equivalent  of  the  liquor  potassae  chlori- 
natae  (U.  S.  P.) 

Potassium  Chlorate — Potassii  chloras  (U.  S.  P.)— KC103— 122.5 
—is  prepared:  (1)  by  passing  Cl  through  a  solution  of  KOH;  (2) 
by  passing  Cl  over  a  mixture  of  milk  of  lime  and  KC1,  heated  to 
60°;  (3)  by  electrolysis  of  KC1.  By  electrolytic  action  the  KC1  is 
split  into  its  ions:  2KC1— 2K+2C1 ;  these,  by  secondary  reactions 
with  H20,  produce  KC10:  K2+2H20=2KOH-f  H2,  and  2KOH+ 
C12=2KC10+H,,  and  at  the  temperature  generated,  the  KC10  yields 
KC103:  2KC10+H20=KC103+KC1+H2.  It  crystallizes  in  trans- 
parent, anhydrous  plates,  soluble  in  H20 ;  sparingly  soluble  in  weak 
alcohol. 

It  fuses  at  400  ° ;  if  further  heated,  it  is  decomposed  into  KC1 
and  perchlorate,  and  at  a  still  higher  temperature  the  perchlorate 
is  decomposed  into  KC1  and  0 : 

2KC103=KC104+KC1+02,  and  KC04=KC1+202. 

It  is  a  valuable  source  of  0,  and  a  more  active  oxidant  than  KN03. 
When  mixed  with  readily  oxidizable  substances,  C,  S,  P,  sugar, 
tannin,  resins,  etc.,  the  mixtures  explode  when  subjected  to  shock. 
With  strong  H2S04  it  gives  off  C1204,  an  explosive  yellow  gas.  It 
is  decomposed  by  HN03  with  formation  of  KN03,  KC104,  and  libera- 
tion of  Cl  and  0.  Heated  with  HC1  it  gives  off  a  mixture  of  Cl  and 
C1204,  the  latter  acting  as  an  energetic  oxidant  in  solutions  in  which 
it  is  generated. 

Sulphates. — Dipotassic  sulphate — Potassium  sulphate — K,S04 — 
174 — occurs  native;  in  the  ash  of  many  plants;  and  in  solution  in 
mineral  waters.  It  may  be  prepared  by  the  action  of  sulphuric  acid 
on  potassium  carbonate : 


POTASSIUM  159 

K2C03+H2S04=C02+H20+K2S04. 

It  crystallizes  in  right  rhombic  prisms;  hard;  permanent  in  air; 
salt  and  bitter  in  taste ;  soluble  in  H20. 

Monopotassic  Sulphate. — Hydropotassic  sulphate — Acid  sulphate 
— KHS04 — 136 — is  formed  as  a  by-product  in  the  manufacture  of 
HN03.  When  heated  it  loses  H20,  and  is  converted  into  the  pyro- 
sulphate,  K0S007,  which,  at  a  higher  temperature,  is  decomposed  into 
K2S04  and  S03. 

Dipotassic  Sulphite — Potassic  sulphite — K2S03 — 158 — is  formed  by  sat- 
urating solution  of  K2CO3  with  S02,  and  evaporating  over  H2S04.  It  crystallizes 
in  oblique  rhombohedra;  soluble  in  H20.  Its  solution  absorbs  0  from  the 
air,  with  formation  of  K2S04. 

Potassium  Bichromate — Bichromate  of  potassium — K2Cr207  —  294  —  is 
formed  by  heating  a  mixture  of  chrome  iron  ore  with  KN03,  or  K2C03  in  air; 
extracting  with  H20;  neutralizing  with  dilute  H2S04;  and  evaporating.  It  forms 
large,  reddish-orange  colored  prismatic  crystals;  soluble  in  H20;  fuses  below 
redness,  and  at  a  higher  temperature  is  decomposed  into  O,  potassium  chromate, 
and  chromic  oxide.  Heated  with  HC1,  it  gives  off  Cl. 

Potassium  Permanganate — Potassii  permanganas  (U.  S.  P.)  — 
KMn04 — 158 — is  obtained  by  boiling  a  solution  of  potassium  man- 
ganate  with  water: 

3K2Mn04+2H20=Mn02+4KOH+2KMn04 

It  crystallizes  in  dark  prisms,  almost  black,  with  greenish  reflec- 
tions, which,  yield  a  red  powder  when  broken.  Soluble  in  H20, 
communicating  to  it  a  red  color,  even  in  very  dilute  solution.  It  is  a 
most  valuable  oxidizing  agent.  With  organic  matter  its  solution  is 
turned  to  green,  by  the  formation  of  the  manganate,  or  deposits  the 
brown  sesquioxide  of  manganese,  according  to  the  nature  of  the  or- 
ganic substance.  In  some  instances  the  reaction  takes  place  best  in 
the  cold,  in  others  under  the  influence  of  heat ;  in  some  better  in  acid 
solutions,  in  others  in  alkaline  solutions.  Mineral  reducing  agents 
act  more  rapidly.  Its  strong  oxidizing  powers  render  its  solutions 
valuable  as  disinfectants.  When  used  as  a  disinfectant  it  is  split  up 
as  follows: 

4KMn04+2H20=4Mn02+4KOH+302 

Potassium  Acetate — Potassii  acetas  (U.  S.  P)—  CH3.COOK— 
110 — exists  in  the  sap  of  plants ;  and  it  is  by  its  calcination  that  the 
major  part  of  the  carbonate  of  wood  ashes  is  formed.  It  is  prepared 
by  neutralizing  acetic  acid  with  K2C03  or  KHC03 : 

K2C03+2CH3.COOH=C02+H20+2CH3.COOK 

It  forms  crystalline  needles,  deliquescent,  and  very  soluble  in  H20 ; 
less  soluble  in  alcohol.  Its  solutions  are  faintly  alkaline. 

Carbonates. — Potassium  Carbonate — Dipotassic  Carbonate — 
Salt  of  tartar— Pearl  ash— Potassii  carbonas  (U.  S.  P.)— K2C03— 


160  TEXT-BOOK   OF   CHEMISTRY 

138 — exists  in  mineral  waters,  and  in  the  animal  economy.  It  is 
prepared  industrially,  in  an  impure  form,  known  as  potash  or  pearl- 
ash,  from  wood  ashes,  from  the  molasses  of  beet  sugar,  and  from  the 
native  Strassfurt  chloride.  It  is  obtained  pure  by  decomposing  the 
monopotassic  salt,  purified  by  several  recrystallizations,  by  heat: 

2KHC03=rC02+H20+K2C03 

or  by  calcining  a  potassium  salt  of  an  organic  acid.  Thus  cream 
of  tartar,  mixed  with  nitre  and  heated  to  redness,  yields  a  black 
mixture  of  C  and  K2C03,  called  black  flux;  on  extracting  which 
with  H20,  a  pure  carbonate,  known  as  salt  of  tartar,  is  dissolved. 

Anhydrous,  it  is  a  white,  granular,  deliquescent,  very  soluble  pow- 
der. At  low  temperatures  it  crystallizes  with  2Aq.  Its  solution  is 
alkaline. 

Monopotassic  Carbonate — Hydropotassic  carbonate — Potassium 
bicarbonate — Potassii  bicarbonas  (U.  S.  P)— HKC03— 100— is  ob- 
tained by  dissolving  K2C03  in  H20,  and  saturating  the  solution 
with  C02: 

K2C03+C02+H20=2KHC03 

It  crystallizes  in  oblique  rhombic  prisms,  much  less  soluble  than 
the  carbonate.  In  solution,  it  is  gradually  converted  into  the 
dipotassic  salt  when  heated,  when  brought  into  a  vacuum,  or  when 
treated  with  an  inert  gas.  The  solutions  are  alkaline  in  reaction  and 
in  taste,  but  are  not  caustic. 

The  substance  used  in  baking,  under  the  name  salaeratus,  is  this 
or  the  corresponding  Na  salt,  usually  the  latter.  Its  extensive  use  in 
some  parts  of  the  country  is  undoubtedly  in  great  measure  the  cause 
of  the  prevalence  of  dyspepsia.  When  used  alone  in  baking,  it 
"raises"  the  bread  by  decomposition  into  carbon  dioxide  and  dipo- 
tassic (or  disodic)  carbonate,  the  latter  producing  disturbances  of 
digestion  by  its  strong  alkaline  reaction. 

Monopotassic  Oxalate — KHC2O4 — 128 — forms  transparent,  soluble,  acid 
needles.  It  occurs  along  with  the  quadroxalate  HKC2O4,  H2C2O4-f-2Aq,  in  salt 
of  lemon  or  salt  of  sorrel,  used  in  straw  bleaching,  and  for  the  removal  of 
ink-stains,  etc.  It  closely  resembles  Epsom  salt  in  appearance,  and  has  been 
fatally  mistaken  for  it. 

Tartrates. — Dipotassic  Tartrate — Potassium  tartrate — Soluble 
tartar — Neutral  tartrate  of  potash — K2C4H400 — 226 — is  prepared  by 
neutralizing  the  hydropotassic  salt  with  potassium  carbonate: 

K2C03+2KHC4H4106=C02+H20+2K2C4H406. 

It  forms  a  white,  crystalline  powder,  very  soluble  in  H20,  the 
solution  being  dextrogyrous,  [a]  D= -(-28.48° ;  soluble  in  alcohol. 
Acids,  even  acetic,  decompose  its  solution,  with  precipitation  of  the 
monopotassic  salt. 


POTASSIUM 


161 


The  constitution  and  relation  of  the  tartrates  may  be  seen  by  a 
study  of  their  graphic  formulae : 

COOH  COOK 

CHOH  CHOH 

CHOH  CHOH 

COOH  COOH 


COOK 

COONa 

COO(SbO) 

CHOH 

CHOH 

CHOH 

CHOH 

CHOH 

CHOH 

COOK 

COOK 

COOK 

Dipotassic 

Sodium  and 

Antimonyl- 

Tartrate 

Potassium   Tartrate 

Potassium   Tartrate 

Tartaric  Acid        Monopotassic 
Tartrate 

Monopotassic  Tartrate — Hydropotassic  tartrate — Cream  of  tar- 
tar— Potassii  bitartras  (U.  S.  P.) — Acid  potassium  tartrate — Po- 
tassium bitartrate — HKC4H400 — 188. — During  the  fermentation  of 
grape  juice,  as  the  proportion  of  alcohol  increases,  crystalline  crusts 
collect  in  the  cask.  These  constitute  the  crude  tartar,  or  argol,  of 
commerce,  which  is  composed,  in  great  part,  of  monopotassic  tartrate, 
with  some  calcium  tartrate  and  coloring  matter.  The  crude  product 
is  purified  by  repeated  crystallization  from  boiling  H20,  decolorizing 
with  animal  charcoal,  digesting  the  purified  tartar  with  HC1  at 
20°,  washing  with  cold  H20,  and  crystallizing  from  hot  H20. 

It  crystallizes  in  hard,  opaque  (translucent  when  pure),  rhombic 
prisms,  which  have  an  acidulous  taste,  and  are  very  sparingly  soluble 
in  H20,  still  less  soluble  in  alcohol.  Its  solution  is  acid,  and  dis- 
solves many  metallic  oxides  with  formation  of  double  tartrates.  When 
boiled  with  antimony  trioxide,  it  forms  tartar  emetic. 

It  is  used  in  the  household,  combined  with  monosodie  carbonate, 
in  baking,  the  two  substances  reacting  upon  each  other  to  form 
Rochelle  salt,  with  liberation  of  carbon  dioxide. 

Baking  Powders  are  now  largely  used  as  substitutes  for  yeast  to  "  raise  " 
biscuits,  cakes,  etc.  Their  action  is  based  upon  the  decomposition  of  HNaCO3 
by  some  salt  having  an  acid  reaction,  or  by  a  weak  acid.  In  addition  to  the 
bicarbonate  and  flour,  or  cornstarch  (added  to  render  the  bulk  convenient  to 
handle  and  to  diminish  the  rapidity  of  the  reaction),  they  contain  cream  of 
tartar,  tartaric  acid,  alum,  or  acid  phosphates. 

Some  of  the  reactions  by  which  the  C02  may  be  liberated  are: 

+      C02 

Carbon 
dioxide 

-f  2C02 
Carbon 
dioxide 

6NaHCO3      =      K2SO4      -f      3Na2S04      -f- 

Monosodic  Dipotassic  Disodic 

carbonate.  sulphate.  sulphate. 


(1)     HKC4H4Oa  -f 

Monopotassic 
tartrate. 

NaHC03 

Monosodie 
carbonate. 

=      NaKC4H406 

Sodium  potassium 
tartrate. 

+      H*0 
Water. 

(2)     H2C4H406      + 

Tartaric   acid. 

2NaHCO3 

Monosodie 
carbonate. 

=      Na2C4H4O6      . 
Disodic  tartrate. 

4-       2H20 
Water. 

(3)       A12(S04)3,K2S04 

Aluminium 
potassium   alum. 


-+-        A1206H6  -f        6C02 

Aluminium  Carbon 

hydroxide.  dioxide. 

(4)     A12(S04)3      -f      6NaHC03      =  3Na2S04     -f     A1206H6     -f     6C02 

Aluminium                      Monosodie  Disodic                 Aluminium               Carbon 

sulphate.                       carbonate.  sulphate.               hydroxide.                dioxide. 


162  TEXT-BOOK   OF   CHEMISTRY 

Sodium  Potassium  Tartrate— Rochelle  salt— Potassii  et  sodii 
tartras  (U.  S.  P.)—  NaKC4H406+4Aq— 210+72— is  prepared  by 
saturating  monopotassic  tartrate  with  disodic  carbonate.  It  crystal- 
lizes in  large,  transparent  prisms,  which  effloresce  superficially  in  dry 
air  and  attract  moisture  in  damp  air.  It  fuses  at  70°-80°,  and  loses 
3Aq  at  100°.  It  is  soluble  in  1.4  parts  of  cold  H,0. 

Potassium  Antimonyl  Tartrate — Tartrated  antimony — Tartar 
emetic— Antimonii  et  potassii  tartras  (U.  S.  P.)  —  (SbO)KC4H,06+ 
i/2Aq— 331.6— is  prepared  by  boiling  a  mixture  of  3  pts.  Sb203  and 
4  pts.  HKC4H406  in  H,0  for  an  hour,  filtering,  and  allowing  to 
crystallize : 

2KHC4HA+SbA=H20+2(SbO)K.C4H4Ofl 

It  crystallizes  in  transparent,  soluble,  right  rhombic  octahedra, 
which  turn  white  in  air.  Its  solutions  are  acid  in  reaction,  have  a 
nauseating  metallic  taste,  and  are  precipitated  by  alcohol.  The  crys- 
tals contain  l/2  Aq,  which  they  lose  entirely  at  100°,  and,  partially 
by  exposure  to  air.  It  is  decomposed  by  the  alkalies,  alkaline  earths, 
and  alkaline  carbonates,  with  precipitation  of  Sb203.  The  precipi- 
tate is  redissolved  by  excess  of  soda  or  potash,  or  by  tartaric  acid. 
HC1,  H2S04  and  HN03  precipitate  corresponding  antimonyl  com- 
pounds from  solutions  of  tartar  emetic.  It  converts  mercuric  into 
mercurous  chloride.  It  forms  double  tartrates  with  the  tartrates  of 
the  alkaloids. 

Potassium  Cyanide. — KCN — 65 — is  obtained  by  heating  a  mix- 
ture of  potassium  ferrocyanide  and  dry  K2C03,  as  long  as  efferves- 
cence continues;  decanting  and  crystallizing: 

K4Fe(CN)6+K2C03=KCNO+Fe+C02+5KCN 

It  is  usually  met  with  in  dull,  white,  amorphous  masses.  Odorless 
when  dry,  it  has  the  odor  of  hydrocyanic  acid  when  moist.  It  is  deli- 
quescent, and  very  soluble  in  H20 ;  almost  insoluble  in  alcohol.  Its 
solution  is  acrid  and  bitter  in  taste,  with  an  after-taste  of  hydrocyanic 
acid.  It  is  very  readily  oxidized  to  the  cyanate,  a  property  which 
renders  it  valuable  as  a  reducing  agent.  Solutions  of  KCN  dissolve 
I,  AgCl,  the  cyanides  of  Ag  and  Au,  and  many  metallic  oxides. 

It  is  actively  poisonous,  and  produces  its  effects  by  decomposition 
and  liberation  of  hydrocyanic  acid  (q.v.). 

Potassium  Ferrocyanide — Yellow  prussiate  of  potash— K4Fe  ( CN )  a-f 
3  Aq — 368-f-54. — This  salt,  the  source  of  the  other  cyanogen  compounds,  is 
manufactured  by  adding  nitrogenous  organic  matter  (blood,  bones,  hoofs, 
leather,  etc.)  and  iron  to  K2CO3  in  fusion;  or  by  other  processes  in  which  the 
N  is  obtained  from  the  residues  of  the  purification  of  coal  gas,  from  atmos- 
pheric air,  or  from  ammoniacal  compounds. 

It  forms  soft,  flexible,  lemon-yellow  crystals,  permanent  in  air  at  ordinary 
temperatures.  They  begin  to  lose  Aq  at  60°,  and  become  anhydrous  at  100°. 
Soluble  in  H20;  insoluble  in  alcohol,  which  precipitates  it  from  its  aqueous 
solution.  When  calcined  with  KOH  or  K,('():I  potassium  cyanide  and  cyanate 


CESIUM   AND  RUBIDIUM  163 

are  formed,  and  Fe  is  precipitated.  Heated  with  dilute  H2S04,  it  yields  an 
insoluble  white  or  blue  salt,  potassium  sulphate,  and  hydrocyanic  acid.  Its 
solutions  form,  with  those  of  many  of  the  metallic  salts,  insoluble  f errocyanides ; 
those  of  Zn,  Pb,  and  Ag  are  white,  cupric  ferrocyanide  is  mahogany-colored, 
ferrous  ferrocyanide  is  bluish  white,  ferric  ferrocyanide,  Prussian  blue,  is  dark 
blue.  Blue  ink  is  a  solution  of  Prussian  blue  in  a  solution  of  oxalic  acid. 

Potassium  Ferricyanide — Red  prussiate  of  potash — K3Fe(CN)6 — 329 — is 
prepared  by  acting  upon  the  ferrocyanide  with  chlorine;  or,  better,  by  heating 
the  white  residue  of  the  action  of  H2S04  upon  potassium  ferrocyanide,  in  the 
preparation  of  hydrocyanic  acid,  with  a  mixture  of  1  vol.  HN03  and  20  vols.  H2O; 
the  blue  product  is  digested  with  H2O,  and  potassium  ferrocyanide,  the  solution 
filtered  and  evaporated.  It  forms  red,  oblique  rhombic  prisms,  almost  insoluble 
in  alcohol.  With  solutions  of  ferrous  salts  it  gives  dark  blue  precipitate, 
Turnbull's  blue. 

Analytical  Characters. —  (1)  Platinic  chloride,  in  presence  of 
HC1:  yellow  ppt,  K2PtCl6;  crystalline  if  slowly  formed;  sparingly 
soluble  in  H20,  much  less  so  in  alcohol.  (2)  Tartaric  acid  in  not  too 
dilute  solution:  white  ppt.;  soluble  in  alkalies  and  in  concentrated 
acids.  (3)  Hydrofiuosilicic  acid:  translucent,  gelatinous  ppt.;  forms 
slowly;  soluble  in  strong  alkalies.  (4)  Perchloric  acid:  white  ppt.; 
sparingly  soluble  in  H,0;  insoluble  in  alcohol.  (5)  Phosphomolyb- 
dic  acid:  white  ppt.;  forms  slowly.  (6)  Colors  the  Bunsen  flame 
violet  (the  color  is  only  observable  through  blue  glass  in  the  presence 
of  Na),  and  exhibits  a  spectrum  of  two  bright  lines:  A  =7860  and 
4045  (Fig.  16,  No.  3,  p.  150). 

Action  of  the  Sodium  and  Potassium  Compounds  on  the  Economy. — 
The  hydroxides  of  Na  and  K,  and  in  a  less  degree  the  carbonates,  disintegrate 
animal  tissues,  dead  or  living,  with  which  they  come  in  contact,  and,  by  virtue 
of  this  action,  act  as  powerful  caustics  upon  a  living  tissue.  Upon  the  skin, 
they  produce  a  soapy  feeling,  and  in  the  mouth  a  soapy  taste.  Like  the  acids, 
they  cause  death,  either  immediately,  by  corrosion  or  perforation  of  the  stomach; 
or,  secondarily,  after  weeks  or  months,  by  closure  of  one  or  both  openings  of 
the  stomach,  due  to  thickening,  consequent  upon  inflammation. 

The  treatment  consists  in  the  neutralization  of  the  alkali  by  an  acid,  dilute 
vinegar.  Neutral.  Neutral  oils  and  milk  are  of  service,  more  by  reason  of 
their  emollient  action  than  for  any  power  they  have  to  neutralize  the  alkali, 
by  the  formation  of  a  soap,  at  the  temperature  of  the  body. 

The  other  compounds  of  Na,  if  the  acid  is  not  poisonous,  are  without 
deleterious  action,  unless  taken  in  excessive  quantity.  Common  salt  has  pro- 
duced paralysis  and  death  in  a  dose  of  half  a  pound.  The  neutral  salts  of  K, 
on  the  contrary,  are  by  no  means  without  true  poisonous  action  when  taken 
internally,  or  injected  subcutaneously,  in  sufficient  quantities;  causing  dyspnea, 
convulsions,  arrest  of  the  heart's  action,  and  death.  In  the  adult  human  subject, 
death  has  followed  the  ingestion  of  doses  of  15-30  gms.  of  the  nitrate,  in 
several  instances;  doses  of  8-60  gms.  of  the  sulphate  have  also  proved  fatal. 

CAESIUM  AND  RUBIDIUM. 

Caesium — Symbol  =  Cs — Atomic  weight  =  133 — (International^ 
132.81;  and  Rubidium — Symbol=Itb — Atomic  weig~ht=85 — Inter- 
rw£«MaZ=85.45)  ;  are  two  rare  elements,  discovered  in  1860  by  Kirch- 


164  TEXT-BOOK   OP   CHEMISTRY 

off  and  Bunsen  while  examining  spectroscopically  the  ash  of  a  spring 
water.  They  exist  in  very  small  quantity  in  lepidolite.  They  combine 
with  0  and  decompose  H20  even  more  energetically  than  does  K, 
forming  strongly  alkaline  hydroxides. 

SILVER. 

Symbol=:Ag  (Argentum) — Atomic  weight— 108 — (International 
=107.88)— Molecular  w eight =216— S p.  0r.=10.4-10.54. 

Although  silver  is  usually  classed  with  the  " noble  metals,"  it 
differs  from  Au  and  Pt  widely  in  its  chemical  characters,  in  which  it 
more  closely  resembles  the  alkaline  metals. 

Silver  occurs  free  in  nature,  also  in  combination  as  the  sulphide 
or  chloride;  it  is  frequently  contained  in  other  sulphides,  notably 
those  of  Sb,  Pb,  and  Cu. 

When  pure  Ag  is  required,  coin  silver  is  dissolved  in  HNO:}  and 
the  diluted  solution  precipitated  with  HC1.  The  silver  chloride  is 
washed,  until  the  washings  no  longer  precipitate  with  silver  nitrate ; 
and  reduced,  either  (1)  by  suspending  it  in  dilute  H2S04  in  a  plati- 
num basin,  with  a  bar  of  pure  Zn,  and  washing  thoroughly,  after 
complete  reduction;  or  (2)  by  mixing  it  with  chalk  and  charcoal 
(AgCl,  100  parts;  C,  5  parts;  CaC03,  70  parts),  and  gradually  intro- 
ducing the  mixture  into  a  red-hot  crucible. 

Silver  is  a  white  metal;  very  malleable  and  ductile;  the  best 
known  conductor  of  heat  and  electricity.  It  is  not  acted  on  by  pure 
air,  but  is  blackened  in  air  containing  a  trace  of  H2S.  It  combines 
directly  with  Cl,  Br,  I,  S,  P,  and  As.  Hot  H2S04  dissolves  it  as  sul- 
phate, and  HN03  as  nitrate.  The  caustic  alkalies  do  not  affect  it. 
It  alloys  readily  with  many  metals;  its  alloy  with  Cu  is  harder  than 
the  pure  metal. 

Silver  seems  to  exist  in  a  number  of  allotropic  modifications,  be- 
sides that  in  which  it  is  ordinarily  met  with.  In  one  of  these  it  is 
brilliant,  metallic,  bluish  green  in  color,  and  dissolves  in  H20,  form- 
ing a  deep  red  solution  •  in  another  it  has  the  color  of  burnished  gold, 
when  dry ;  and  in  still  another  it  has  also  a  bluish  green  color,  but  is 
insoluble  in  water.  Very  dilute  mineral  acids  immediately  convert 
these  modifications  into  normal  gray  silver,  without  evolution  of  any 
gas. 

Oxides. — Three  oxides  of  silver  are  known:  Ag40,  Ag.,0,  and 
Ag202. 

Silver  Monoxide— Argenti  oxidum— (U.  S.  P.)— Ag,0— 232— 
formed  by  precipitating  a  solution  of  silver  nitrate  with  potash: 

2AgN03+2KOH=2KN03+H20+Ag20 

It    is   a   brownish   powder;    faintly    alkaline   and   very   slightly 


AMMONIUM   COMPOUNDS  165 

soluble  in  HoO ;  strongly  basic.    It  readily  gives  up  its  oxygen.    On 
contact  with  ammonium  hydroxide  it  forms  a  fulminating  powder. 

Silver  Chloride — AgCl — 143.5 — formed  when  HC1  or  a  chloride  is  added  to 
a  solution  containing  silver.  It  is  white;  turns  violet  and  black  in  sunlight; 
volatilizes  at  260°;  sparingly  soluble  in  HC1;  soluble  in  solutions  of  the  alkaline 
chlorides,  thiosulphates,  and  cyanides,  and  in  ammonium  hydroxide.  It  crystal- 
lizes in  octahedra  on  exposure  of  its  ammoniacal  solution. 

Silver  Bromide — AgBr — and  Iodide — Agl — are  yellowish  precipitates, 
formed  by  decomposing  silver  nitrate  with  potassium  bromide  and  iodide.  The 
former  is  very  sparingly  soluble  in  ammonium  hydroxide,  the  latter  is  insoluble. 

Silver  Nitrate— Argenti  nitras  (U.  S.  P.)— AgN03— 170— is 
prepared  by  dissolving  Ag  in  HN03,  evaporating,  fusing,  and  re- 
crystallizing.  It  crystallizes  in  anhydrous,  right  rhombic  plates; 
soluble  in  H20.  The  solutions  are  colorless  and  neutral.  In  the 
presence  of  organic  matter  it  turns  black  in  sunlight. 

The  salt,  fused  and  cast  into  cylindrical  moulds,  constitutes  lunar 
caustic,  lapis  infernalis;  argenti  nitras  fusus  (U.  S.  P.).  If,  during 
fusion,  the  temperature  is  raised  too  high,  it  is  converted  into  nitrite, 
0,  and  Ag ;  and  if  sufficiently  heated  leaves  pure  Ag. 

Dry  Cl  and  I  decompose  it,  with  liberation  of  anhydrous  HN03. 
It  absorbs  NH3,  to  form  a  white  solid,  AgN03,  3NH3,  which  gives  up 
its  NH3  when  heated.  Its  solution  is  decomposed  very  slowly  by  H, 
with  deposition  of  Ag. 

Analytical  Characters. — (1)  Hydrochloric  acid:  white  flocculent 
ppt. ;  soluble  in  NH4OH;  insoluble  in  HN03.  (2)  Potash  or  soda: 
brown  ppt.;  insoluble  in  excess;  soluble  in  NH4OH.  (3)  Ammonium 
hydroxide,  from  neutral  solutions :  brown  ppt. ;  soluble  in  excess.  (4) 
Hydrogen  sulphide  or  ammonium  sulphydrate :  black  ppt.  insoluble  in 
NH4HS.  (5)  Potassium  bromide:  yellowish  white  ppt.;  insoluble  in 
acids,  if  not  in  great  excess;  soluble  in  NH4OH.  (6)  Potassium 
iodide :  same  as  KBr,  but  the  ppt.  is  less  soluble  in  NH4OH. 

Action  on  the  Economy. — Silver  nitrate  acts  both  locally  as  a  corrosive, 
and  systemically  as  a  true  poison.  Its  local  action  is  due  to  its  decomposition, 
by  contact  with  organic  substances,  resulting  in  the  separation  of  elementary 
Ag,  whose  deposition  causes  a  black  stain,  and  liberation  of  free  HNO3,  which 
acts  as  a  caustic.  When  absorbed,  it  causes  nervous  symptoms,  referable  to  its 
poisonous  action.  The  blue  coloration  of  the  skin,  observed  in  those  to  whom 
it  is  administered  for  some  time,  is  due  to  the  reduction  of  the  metal,  under 
the  combined  influence  of  light  and  organic  matter;  especially  of  the  latter,  as 
the  darkening  is  observed,  although  it  is  less  intense,  in  internal  organs. 

In  acute  poisoning  by  silver  nitrate,  sodium  chloride  or  white  of  egg  should 
be  given;  and,  if  the  case  is  seen  before  the  symptoms  of  corrosion  are  far 
advanced,  emetics. 

AMMONIUM  COMPOUNDS. 

The  Ammonium  Theory. — Although  neither  the  radical  ammo- 
nium, NH4,  nor  the  molecule  (NH4)2  has  ever  been  isolated,  the 
existence  of  the  radical  in  the  ammoniacal  compounds  is  almost  uni- 


166  TEXT-BOOK   OF   CHEMISTRY 

versally  admitted.  The  ammonium  hypothesis  is  based  chiefly  upon 
the  following  facts:  (1)  the  close  resemblance  of  the  ammoniacal 
salts  to  those  of  K  and  Na;  (2)  when  ammonia  gas  and  an  acid  gas 
come  together,  they  unite,  without  liberation  of  hydrogen,  to  form 
an  ammonium  salt;  (3)  when  solutions  of  the  ammoniacal  salts  are 
subjected  to  electrolysis,  a  mixture,  having  the  composition  NH3-fH 
is  given  off  at  the  negative  pole;  (4)  amalgam  of  sodium,  in  contact 
with  a  concentrated  solution  of  ammonium  chloride,  increases  much 
in  volume,  and  is  converted  into  a  light,  soft  mass,  having  the  luster 
of  mercury.  This  ammonium  amalgam  is  decomposed  gradually, 
giving  off  ammonia  and  hydrogen  in  the  proportion  NH3+H;  (5)  if 
the  gases  NH3+H,  given  off  by  decomposition  of  the  amalgam,  exist 
there  in  simple  solution,  the  liberated  H  would  have  the  ordinary 
properties  of  that  element.  If,  on  the  other  hand,  they  exist  in  com- 
bination, the  H  would  exhibit  the  more  energetic  affinities  of  an 
element  in  the  nascent  state.  The  hydrogen  so  liberated  is  in  the 
nascent  state. 

Ammonium  Hydroxide — Caustic  ammonia — NH4OH — 35 — has 
never  been  isolated,  probably  owing  to  its  tendency  to  decomposition ; 
NH4OH=NH3-}-H20.  It  is  considered  as  existing  in  the  so-called 
aqueous  solutions  of  ammonia.  These  are  colorless  liquids;  of  less 
sp.  gr.  than  H20 ;  strongly  alkaline ;  and  having  the  taste  and  odor 
of  ammonia,  which  gas  they  give  off  on  exposure  to  air,'  and  more 
rapidly  when  heated.  They  are  neutralized  by  acids,  with  elevation 
of  temperature  and  formation  of  ammoniacal  salts.  The  Aqua  am- 
moniae  and  Aqua  ammonias  fortior  (U.  S.  P.)  are  such  solutions; 
the  former  contains  about  10  per  cent,  and  the  latter  28  per  cent, 
of  NH3. 

Ammonium  Hydrogen  Sulphide — Ammonium  Sulphydrate — N4HS — 51 — 
is  formed,  in  solution  by  saturating  a  solution  of  NH4HO  with  H2S;  or,  an- 
hydrous, by  mixing  equal  volumes  of  dry  NH3  and  dry  H2S. 

The  anhydrous  compound  is  a  colorless,  transparent,  volatile  and  soluble 
solid.  The  solution,  when  freshly  prepared,  is  colorless,  but  soon  becomes  yellow 
from  oxidation,  and  formation  of  ammonium  disulphide  and  thiosulphate,  and 
finally  deposits  sulphur. 

The  sulphides  and  hydrosulphide  of  ammonium  are  also  formed  during  the 
decomposition  of  protein  bodies,  and  exist  in  the  gases  formed  in  burial  vaults, 
sewers,  etc. 

Ammonium  Chloride — Sal  ammoniac — Ammonii  chloridum  (U. 
S.  P) — NH4C1 — 53.5 — is  obtained  from  the  ammoniacal  water  of 
gas  works.  It  is  a  translucid,  fibrous,  elastic  solid;  salty  in  taste, 
neutral  in  reaction ;  volatile  without  fusion  or  decomposition ;  soluble 
in  H.,O.  Its  solution  is  neutral,  but  loses  NH3  and  becomes  acid 
when  boiled. 

Ammonium  chloride  exists  in  small  quantity  in  the  gastric  juice 
of  the  sheep  and  dog;  also  in  the  perspiration,  urine,  saliva  and  tears. 


AMMONIUM    COMPOUNDS  167 

Ammonium  Bromide— Ammonii  bromidum  (U.  S.  P.)  —  (NH4)Br — 98 

is  formed  either  by  combining  NH3  and  HBr;  by  decomposing  ferrous  bromide 
with  NH4OH;  or  by  double  decomposition  between  KBr  and  (NH4)2SO4.  It  is  a 
white,  granular  powder,  or  crystallizes  in  large  prisms,  which  turn  yellow  on 
exposure  to  air;  quite  soluble  in  H2O;  volatile  without  decomposition. 

Ammonium  Iodide— Ammonii  iodidum  (U.  S.  P.)—  NHJ— 145— is  formed 
by  union  of  equal  volumes  of  NH3  and  HI;  or  by  double  decomposition  of  KI 
and  (NH4)2S04.  It  crystallizes  in  deliquescent,  very  soluble  cubes. 

Ammonium  Nitrate— (NH4)N03— 80— is  prepared  by  neutralizing  HN03 
with  ammonium  hydroxide  or  carbonate.  It  crystallizes  in  flexible,  anhydrous, 
six-sided  prisms;  very  soluble  in  H2O,  with  considerable  diminution  of  tem- 
perature; fuses  at  150°,  and  decomposes  at  210°,  with  formation  of  nitrous 
oxide:  (NH4)NO3=:N20-f 2H2O.  If  the  heat  is  suddenly  applied,  or  allowed  to 
surpass  250°,  NH2,  NO.  and  N20  are  formed.  When  fused  it  is  an  active  oxidant. 

Sulphates. — Diammonic  Sulphate — Ammonic  sulphate — (NH4)2S04 — 132 — 
is  obtained  by  collecting  the  distillate  from  a  mixture  of  ammoniacal  gas 
liquor  and  lime  in  H2S04.  It  forms  anhydrous,  soluble,  rhombic  crystals;  fuses 
at  150°,  and  is  decomposed  at  200°  into  NH3  and  H(NH4)S04. 

Monoammonic  Sulphate — Hydroammonic  sulphate — Bismuth  of  ammonia — 
H(NH4)S04— 115— is  formed  by  the  action  of  H2S04  on  (NH4)2SO4.  It  crystal- 
lizes in  right  rhombic  prisms,  soluble  in  H20  and  in  alcohol. 

Ammonium  Acetate — (NH4)C2H302 — 77 — is  formed  by  saturating  acetic 
acid  with  NH3,  or  with  ammonium  carbonate.  It  is  a  white,  odorless,  very 
soluble  solid;  fuses  at  86°,  and  gives  off  NH3;  then  acetic  acid,  and  finally 
acetamide.  Liquor  ammonii  acetatis  (U.  S.  P. )=Spirit  of  Minderus  is  an 
aqueous  solution  of  this  salt,  containing  not  less  than  7  per  cent,  of  ammonium 
acetate. 

Ammonium  Sesquicarbonate — Ammonium  Carbonate — Sal  vola- 
tile—Preston salts— Ammonii  carbonas  (U.  S.  P.)  ;— NH4HC03+ 
NH4C02NH2 — 157 — is  prepared  by  heating  a  mixture  of  NH4C1  or 
(NH4)2S04  and  chalk,  and  condensing  the  product.  It  crystallizes  in 
rhombic  prisms;  has  an  ammoniacal  odor  and  an  alkaline  reaction; 
soluble  in  H20.  By  exposure  to  air  or  by  heating  its  solution,  it  is 
decomposed  into  H20,  NH3,  and  H(NH4)C03.  It  is  not  a  pure  salt, 
but  a  mixture  of  monoammonium  carbonate  and  ammonium  car- 
bamate. 

Analytical  Characters. —  (1)  Entirely  volatile  at  high  tempera- 
tures. (2)  Heated  with  KOH,  the  ammoniacal  compounds  give  off 
NH3,  recognizable:  (a)  by  changing  moist  red  litmus  to  blue;  (&)  by 
its  odor;  (c)  by  forming  a  white  cloud  on  contact  with  a  glass  rod 
moistened  with  HC1.  (3)  With  platinic  chloride:  a  yellow,  crystal- 
line ppt. 

Action  on  the  Economy. — Solutions  of  the  hydroxide  and  carbonate  act 
upon  animal  tissues  in  the  same  way  as  the  corresponding  Na  and  K  compounds. 
They,  moreover,  disengage  NH3,  which  causes  intense  dyspnea,  irritation  of  the 
air-passages,  and  suffocation. 

The  treatment  indicated  is  the  neutralization  of  the  alkali  by  a  dilute  acid. 
Usually  the  vapor  of  acetic  acid  or  of  dilute  HC1  must  be  administered  by  in- 
halation. 


168  TEXT-BOOK    OF    CHEMISTRY 

II.    THALLIUM  GROUP. 

THALLIUM. 
-Symbol=Tl—  Atomic  weight—  2Q^—  (International—  2^.^  —  Sp. 


A  rare  element,  first  obtained  from  the  deposits  in  flues  of  sul- 
phuric acid  factories,  in  which  pyrites  from  the  Hartz  were  used.  It 
resembles  Pb  in  appearance  and  in  physical  properties,  but  differs 
entirely  from  that  element  in  its  chemical  characters.  It  resembles 
Au  in  being  univalent  and  trivalent,  but  differs  from  it,  and  resem- 
bles the  alkali  metals  in  being  readily  oxidized,  in  forming  alums,  and 
informing  no  acid  hydrate.  It  differs  from  the  alkali  metals  in  the 
thallic  compounds,  which  contain  TT".  It  is  characterized  spectro- 
scopically  by  a  bright  green  line  —  A=5349. 


III.     CALCIUM  GROUP. 
Metals  of  the  Alkaline  Earths. 
CALCIUM—  STRONTIUM—  BARIUM. 

The  members  of  this  group  are  bivalent  in  all  their  compounds; 
each  forms  two  oxides  :  MO  and  M02  ;  each  forms  a  hydroxide,  having 
well-marked  basic  characters. 

CALCIUM. 

Symbol=Csi  —  Atomic  weight=40  —  (International=40.01)  —  Mo- 
lecular weight=SO—Sp.  #r.=1.984. 

Occurs  only  in  combination,  as  limestone,  marble,  chalk  (CaC03), 
gypsum,  selenite,  alabaster  (CaSOJ,  and  many  other  minerals.  In 
bones,  egg-shells,  oyster-shells,  etc.,  as  Ca3(P04),  and  CaC03,  and 
in  many  vegetable  structures. 

The  element  is  obtained  by  electrolysis  of  fused  CaCL,  or  by  heat- 
ing CaI2  with  Na.  It  is  a  hard,  yellow,  very  ductile,  and  malleable 
metal,  fusible  at  a  red  heat;  not  sensibly  volatile.  In  dry  air  it  is 
not  altered,  but  is  converted  into  CaHo02  in  damp  air;  decomposes 
H20  ;  burns  when  heated  in  air. 

~  Calcium  Oxide—  Quick  Lime—  Lime—  Calx  (U.  S.  P.)—  CaO—  56 
—is  prepared  by  heating  a  native  carbonate  (limestone)  ;  or,  when 
required  pure,  by  heating  a  carbonate,  prepared  by  precipitation: 

CaC03=CaO+C02 


CALCIUM  169 

It  occurs  in  white  or  grayish,  amorphous  masses;  odorless;  alka- 
line, caustic;  almost  infusible;  sp.  gr.  2.3.  With  H20  it  gives  off 
great  neat  and  is  converted  into  the  hydroxide  (slaking).  In  air  it 
becomes  air-slaked,  falling  into  a  white  powder,  having  the  com- 
position CaC03,  CaH,02. 

Calcium  Hydroxide — Calcium  Hydrate — Slaked  lime — Ca(OH)., 
—74 — is  formed  by  the  action  of  H20  on  CaO.  If  the  quantity  of 
H20  used  be  one-third  that  of  the  oxide,  the  hydroxide  remains  as  a 
dry,  white,  odorless  powder;  alkaline  in  taste  and  reaction;  more 
soluble  in  cold  than  in  hot  H,0.  If  the  quantity  of  H20  is  greater, 
a  creamy  or  milky  liquid  remains,  cream,  or  milk  of  lime;  a  solu- 
tion holding  an  excess  in  suspension.  With  a  sufficient  quantity  of 
H20  the  hydroxide  is  dissolved  to  a  clear  solution,  which  is  lime 
water— Liquor  calcis  (U.  S.  P.).  The  solubility  of  Ca(OH)2  is 
diminished  by  the  presence  of  alkalies,  and  is  increased  by  sugar  or 
mannite.  Solutions  of  Ca(OH)2  absorb  C02  with  formation  of  a 
white  deposit  of  CaC03. 

Calcium  Carbide — CaC2 — is  formed  by  the  action  of  a  very  high 
temperature  upon  a  mixture  of  quick  lime  and  carbon.  It  is  an 
amorphous  grayish  substance,  which  is  decomposed  by  water,  yielding 
acetylene  gas:  CaC2+2H20=C2H2+Ca(OH)2.  One  kilo.  CaC2 
yields  440  litres  C2H2. 

Calcium  Chloride— Calcii  chloridum  (U.  S.  P.)— CaCl2— 111— is 
obtained  by  dissolving  marble  in  HC1: 

CaC03+2HCl=CaCl2+H20+C02 

It  is  bitter,  deliquescent,  very  soluble  in  H02 ;  crystallizes  with 
6Aq,  which  it  loses  when  fused,  leaving  a  white,  amorphous  mass, 
used  as  a  drying  agent. 

Chlorinated  Lime — Chloride  of  Lime — Bleaching  powder — Calx 
chlorinata  (U.  S.  P.) — is  a  white  or  yellowish,  hygroscopic  powder, 
prepared  by  passing  Cl  over  Ca(OH)2,  maintained  in  excess.  It  is 
bitter  and  acrid  in  taste ;  soluble  in  cold  H20 ;  decomposed  by  boiling 
H20,  and  by  the  weakest  acids,  with  liberation  of  CL  It  is  decom- 
posed by  C02,  with  formation  of  CaC03,  and  liberation  of  hypo- 
chlorous  acid,  if  it  be  moist ;  or  of  Cl,  if  it  be  dry.  A  valuable  dis- 
infectant. The  "available  chlorine"  is  the  amount  liberated  by  acids, 
and  should  be  not  less  than  30  per  cent. 

Bleaching  powder  was  formerly  considered  as  a  mixture  of  calcium 
chloride  and  hypochlorite,  formed  by  the  reaction:  2CaO-}-2Cl2= 
CaCL+Ca(C10)2,  but  it  is  more  probable  that  it  is  a  definite  com- 
pound having  the  formula  CaCl(OCl),  which  is  decomposed  by  H20 
into  a  mixture  of  CaCl2  and  Ca(C10)2;  and  by  dilute  HN03  or 
H2S04  with  formation  of  HC10. 

Calcium  Sulphate — CaS04 — 136 — occurs  in  nature  as  anhydrite; 
and  with  2Aq  in  gypsum,  alabaster,  selenite;  and  in  solution  in 


170  TEXT-BOOK   OF   CHEMISTRY 

natural  waters.  Terra  alba  is  ground  gypsum.  It  crystallizes  with 
2Aq  in  right  rhombic  prisms ;  sparingly  soluble  in  H20,  more  soluble 
in  H20  containing  free  acids  or  chlorides.  When  the  hydrated  salt 
(gypsum)  is  heated  to  80°,  or,  more  rapidly,  between  120°-130°,  it 
loses  its  Aq  and  is  converted  into  a  white,  opaque  mass,  which,  when 
ground,  is  plaster  of  Paris. 

The  setting  of  plaster  when  mixed  with  H2O,  is  due  to  the  conversion  of 
the  anhydrous  into  the  crystalline,  hydrated  salt.  The  ordinary  plastering 
should  never  be  used  in  hospitals,  as,  by  reason  of  its  irregularities  and  porosity, 
it  soon  becomes  saturated  with  septic  germs,  and  cannot  be  thoroughly  purified 
by  disinfectants.  Plaster  surfaces  may,  however,  be  rendered  dense,  and  be 
highly  polished,  so  as  to  be  smooth  and  impermeable,  by  adding  glue  and  alum, 
or  an  alkaline  silicate  to  the  water  used  in  mixing. 

Calcium  Phosphate — Tricalcic  Phosphate — Tribasic  or  neutral 
phosphate — Bone  Phosphate — Phosphate  of  Lime — Ca3(P04)2— 
310 — occurs  in  nature,  in  soils,  guano,  coprolites,  phosphorite,  in  all 
plants,  and  in  every  animal  tissue  and  fluid.  It  is  obtained  by  dis- 
solving bone-ash  in  HC1,  filtering,  and  precipitating  with  NH4OH; 
or  by  double  decomposition  between  CaCl,  and  an  alkaline  phosphate. 
When  freshly  precipitated  it  is  gelatinous;  when  dry,  a  light,  white, 
amorphous  powder ;  almost  insoluble  in  pure  H20 ;  soluble  to  a  slight 
extent  in  H20  containing  ammoniacal  salts,  or  NaCl  or  NaN03; 
readily  soluble  in  dilute  acids,  even  in  H20  charged  with  carbonic 
acid.  It  is  decomposed  by  H,S04  into  CaS04  and  Ca(H2P04)2. 
Bone-ash  is  an  impure  form  of  Ca3(P04)2,  obtained  by  calcining 
bones,  and  used  in  the  manufacture  of  P  and  of  superphosphate. 

Calcium  Carbonate — CaC03 — 100 — the  most  abundant  of  the 
natural  compounds  of  Ca,  exists  as  limestone,  calcspar,  chalk,  marble, 
Iceland  spar,  and  arragonite;  and  forms  the  basis  of  corals,  shells  of 
Crustacea  and  of  molluscs,  etc.  Otoliths,  which  occur  in  the  internal 
ear,  parotid  calculi,  and  sometimes  vesical  calculi  consist  of  CaC03. 

Precipitated  chalk — Calcii  carbonas  praecipitatus  (U.  S.  P.) — is 
prepared  by  precipitating  a  solution  of  CaCl2  with  one  of  Na2C03. 
Prepared  chalk — Creta  praeparata  (U.  S.  P.) — is  native  chalk,  puri- 
fied by  grinding  with  H20,  diluting,  allowing  the  coarser  particles 
to  subside,  decanting  the  still  turbid  liquid,  collecting  and  drying 
the  finer  particles.  Such  a  process  is  known  as  elutriation  or  levi- 
gation. 

It  is  a  white  powder,  almost  insoluble  in  pure  H20;  much  more 
soluble  in  H20  containing  carbonic  acid,  the  solution  being  regarded 
as  containing  monocalcic  carbonate,  H2Ca(C03)2.  At  a  red  heat  it 
yields  CO.,  and  CaO.  It  is  decomposed  by  acids  with  liberation 
of  C02. 

Calcium  Oxalate — Oxalate  of  lime — CaC204 — 128 — exists  in  the 
sap  of  many  plants,  in  human  urine,  and  in  mulberry  calculi,  and  is 


BARIUM  171 

formed  a*s  a  white,  crystalline  precipitate,  by  double  decomposition, 
between  a  Ca  salt  and  an  alkaline  oxalate.  It  is  insoluble  in  H20, 
acetic  acid,  or  NH4OH;  soluble  in  the  mineral  acids  and  in  solution 
of  H2NaP04. 

Analytical  Characters. —  (1)  Ammonium  sulphydrate:  nothing, 
unless  the  Ca  salt  be  the  phosphate,  oxalate  or  fluoride,  when  it  forms 
a  white  ppt.  (2)  Alkaline  carbonates:  white  ppt. ;  not  prevented  by 
the  presence  of  ammoniacal  salts.  (3)  Ammonium  oxalate:  white 
ppt.,  insoluble  in  acetic  acid  ;  soluble  in  HC1  or  HN03.  (4)  Sulphuric 
acid :  white  ppt.,  either  immediately  or  on  dilution  with  three  volumes 
of  alcohol;  very  sparingly  soluble  in  H20,  insoluble  in  alcohol;  sol- 
uble in  sodium  thiosulphate  solution.  (5)  Sodium  tungstate:  dense 
white  ppt.,  even  from  dilute  solutions.  (6)  Colors  the  flame  of  the 
Bunsen  burner  reddish-yellow,  and  exhibits  a  spectrum  of  a  number 
of  bright  bands,  the  most  prominent  of  which  are:  A  =6265,  6202, 
6181,  6044,  5982,  5933,  5543,  and  5517. 

STRONTIUM. 

Symbol  =  Sr — Atomic  weight  =  87.5 — (International  =  87.63)  — 
Sp.  #r.=2.54. 

An  element  not  as  abundant  as  Ba,  occurring  principally  in  the 
minerals  strontianite  (SrCo3)  and  celestine  (SrSOJ.  Its  compounds 
resemble  those  of  Ca  arid  Ba.  Its  nitrate  is  used  in  making  red  fire. 
The  bromide,  iodide,  and  the  salicylate  are  official  in  the  U.  S.  P. 

Analytical  Characters. —  (1)  Behaves  like  Ba  with  alkaline  car- 
bonates and  Na2HP04.  (2)  Calcium  sulphate:  a  white  ppt.,  which 
forms  slowly;  accelerated  by  addition  of  alcohol.  (3)  The  Sr  com- 
pounds color  the  Bunsen  flame  red-,  or,  as  observed  through  blue 
glass,  purple  or  rose  color.  The  Sr  flame  gives  a  spectrum  of  many 
bands,  of  which  the  most  prominent  are :  \  =6694,  6664,  6059,  6031, 
4607. 

BARIUM. 

$i/m&0Z=Ba — Atomic  weight=137 — (International=~[.37.37) — Mo- 
lecular weight=214: — Sp.  gr.=4.0. 

Occurs  only  in  combination,  principally  as  heavy  spar  (BaSOJ 
and  witherite  (BaC03).  It  is  a  pale  yellow,  malleable  metal,  quickly 
oxidized  in  air,  and  decomposing  H20  at  ordinary  temperatures. 

Oxides. — Barium  Monoxide — Baryta — BaO — 153 — is  prepared 
by  calcining  the  nitrate: 

2Ba(N03)2=4N02+02+2BaO 

It  is  a  grayish-white  or  white,  amorphous,  caustic  solid.  In  air 
it  absorbs  moisture  and  C02,  and  combines  with  H20  as  does  CaO. 


172  TEXT-BOOK   OF   CHEMISTRY 

Barium  Dioxide — Ba02 — 169 — is  prepared  by  heating  the 
monoxide  in  0.  It  is  a  grayish-white,  amorphous  solid.  Heated  in 
air  it  is  decomposed :  BaO,=BaO+0.  Aqueous  acids  dissolve  it  with 
formation  of  a  barytic  salt  and  H202. 

Barium  Hydroxide — Ba(OH)2 — 171 — is  prepared  by  the  action 
of  H20  on  BaO.  It  is  a  white,  amorphous  solid,  soluble  in  H20.  Its 
aqueous  solution,  baryta  water,  is  alkaline,  and  absorbs  C02,  with 
formation  of  a  white  deposit  of  BaC03. 

Barium  Chloride— BaCl2+2  Aq— 208+36— is  obtained  by  treat- 
ing BaS  or  BaC03  with  HC1.  It  crystallizes  in  prismatic  plates,  per- 
manent in  air,  soluble  in  H20. 

Barium  Nitrate — Ba(N03)2 — 261 — is  prepared  by  neutralizing  HN03  with 
BaCO3.  It  forms  octahedral  crystals,  soluble  in  H20. 

Barium  Sulphate — BaS04 — 233 — occurs  in  nature  as  heavy  spar,  and  is 
formed  as  an  amorphous,  white  powder,  insoluble  in  acids,  by  double  decomposi- 
tion between  a  Ba  salt  and  a  sulphate  in  solution.  It  is  insoluble  in  H2O 
and  in  acids.  It  is  used  as  a  pigment,  permanent  white. 

Barium  Carbonate — BaCO3 — 197 — occurs  in  nature  as  icitherite,  and  is 
formed  by  double  decomposition  between  a  Ba  salt  and  a  carbonate  in  alkaline 
solution.  It  is  a  heavy,  amorphous,  white  powder,  insoluble  in  H2O,  soluble 
with  effervescence  in  acids. 

Analytical  Characters. — (1)  Alkaline  carbonates:  white  ppt.,  in 
alkaline  solution.  (2)  Sulphuric  acid,  or  calcium  sulphate:  white 
ppt.,  insoluble  in  acids.  (3)  Sodium  phosphate:  white  ppt.,  soluble 
in  HN03.  (4)  Colors  the  Bunsen  flame  greenish -yellow,  and  ex- 
hibits a  spectrum  of  several  lines,  the  most  prominent  of  which 
are:  A=6108,  6044,  5881,  5536. 

Action  on  the  Economy. — The  oxides  and  hydroxide  act  as  corrosives,  by 
virtue  of  their  alkalinity,  and  also  as  true  poisons.  All  soluble  compounds  of 
Ba,  and  those  which  are  readily  converted  into  soluble  compounds  in  the 
stomach,  are  actively  poisonous.  Soluble  sulphides,  followed  by  emetics,  are 
indicated  as  antidotes.  The  sulphate,  notwithstanding  its  insolubility  in  water, 
is  poisonous  to  some  animals. 


IV.    MAGNESIUM  GROUP. 
MAGNESIUM— ZINC— CADMIUM. 

Each  of  these  elements  forms  a  single  oxide — a  corresponding  basic 
hydroxide,  and  a  series  of  salts  in  which  its  atoms  are  bivalent. 

The  existence  of  potassium  zincate,  Zn02K2,  obtainable  by  the 
action  of  zinc  hydroxide  and  potassium  hydroxide  upon  each  other: 
Zn(OH)2+2KOH=Zn02K2+2H20  would  seem  to  require  the  trans- 
ferral  of  zinc  to  the  amphoteric  class;  the  Zn(OH)2  in  the  above  re- 
action fulfilling  the  requirements  of  the  second  definition  of  acids 
(see  p.  178).  Potassium  zincate  should,  however,  be  considered  rather 


MAGNESIUM  173 

as  a  double  oxide  of  zinc  and  potassium:  ZnOK,0  or  Zn.OK.OK, 
than  as  a  true  salt  for  the  following  reasons:  (1)  It  is  also  produced 
by  the  reaction :  Zn+2KOH:=Zn02K2+H2,  in  which,  if  Zn02K2  be 
a  salt,  KOH,  the  most  distinctly  basic  substance  known,  must  be 
considered  to  be  an  acid.  (2)  In  the  electrolysis  of  Zn02K2  the  Zn 
and  K  go  to  the  negative  pole,  and  the  0  to  the  positive,  while  in  the 
electrolysis  of  true  ternary  salts,  such  as  K2S04,  the  oxygen  accom- 
panies the  other  electro-negative  element  to  the  positive  pole,  the 
metal  going  alone  to  the  negative.  Moreover,  the  zincates  are  un- 
stable bodies,  and  the  most  prominent  function  of  Zn(OH)2  is  that 
of  a  base,  as  in  the  reaction  Zn(OH)2+H2S04=ZnS04+2H02. 
(See  Aluminium,  p.  178.) 

MAGNESIUM. 

Symbol=Mg — Atomic  weight— 24 — (International^ :24.32) — Mo- 
lecular weight— 48 — 8p.  gr=1.75. 

Occurs  as  carbonate  in  dolomite  or  magnesium  limestone,  and  as 
silicate  in  mica,  asbestos,  soapstone,  meerschaum,  talc,  and  in  other 
minerals.  It  also  accompanies  Ca  in  the  forms  in  which  it  is  found 
in  the  animal  and  vegetable  worlds. 

It  is  prepared  by  heating  its  chloride  with  Na,  or  by  electrolysis  of 
the  fused  chloride.  It  is  a  hard,  light,  malleable,  ductile,  white 
metal.  It  burns  with  great  brilliancy  when  heated  in  air  (magnesium 
light),  but  may  be  distilled  in  H.  The  flash  light  used  by  photog- 
raphers is  a  mixture  of  powdered  Mg  with  an  oxidizing  agent,  KC103 
or  KN03.  It  decomposes  vapor  of  H20  when  heated;  reduces  C02 
with  the  aid  of  heat,  and  combines  directly  with  Cl,  S,  P,  As  and  N. 
It  dissolves  in  dilute  acids,  but  is  not  affected  by  alkaline  solutions. 

Magnesium  Oxide — Calcined  magnesia — Magnesii  oxidum — 
Magnesia  (U.  S.  P.) — MgO — 40 — is  obtained  by  calcining  the  car- 
bonates, hydroxide,  or  nitrate.  It  is  a  light,  bulky,  tasteless,  odorless, 
amorphous,  white  powder ;  alkaline  in  reaction ;  almost  insoluble  in 
H20 ;  readily  soluble  without  effervescence  in  acids. 

Magnesium  Hydroxide — Mg(OH)2 — 58 — occurs  in  nature,  and  is 
formed  when  a  solution  of  a  Mg  salt  is  precipitated  with  excess  of 
NaOH  in  absence  of  ammoniacal  salts.  It  is  a  heavy,  white  powder, 
insoluble  in  H20,  absorbs  C02. 

Magnesium  Chloride— MgCL — 95 — is  formed  when  MgO  or 
MgC03  is  dissolved  in  HC1.  It  is  an  exceedingly  deliquescent,  soluble 
substance,  which  is  decomposed  into  HC1  and  MgO  when  its  aqueous 
solutions  are  evaporated  to  dryness.  Like  all  the  soluble  Mg  com- 
pounds it  is  bitter  in  taste,  and  accompanies  the  sulphate  and  bicar- 
bonate in  the  bitter  waters. 

Magnesium  Sulphate — Epsom  salt — Seidlitz  salt — Magnesii  sul- 


174  TEXT-BOOK   OF   CHEMISTRY 

phas  (U.  S.  P.)— MgS04+7Aq— 120+126— exists  in  solution  in  sea 
water  and  in  the  waters  of  many  mineral  springs,  especially  those 
known  as  bitter  waters.  It  is  formed  by  the  action  of  H.,S04  on 
MgC03: 

MgC03+H2S04=C02+H20+MgS04 

It  crystallizes  in  right  rhombic  prisms ;  bitter,  slightly  effervescent, 
and  quite  soluble  in  H20.  Heated,  it  fuses  and  gradually  loses  6Aq 
up  to  132°;  the  last  Aq  it  loses  at  210°. 

Phosphates. — Resemble  those  of  Ca  in  their  constitution  and 
properties,  and  accompany  them  in  the  situations  in  which  they  occur 
in  the  animal  body,  but  in  much  smaller  quantity. 

Magnesium  also  forms  double  phosphates,  constituted  by  the 
substitution  of  one  atom  of  the  bivalent  metal  for  two  of  the  atoms 
of  basic  hydrogen,  of  a  molecule  of  phosphoric  acid,  and  of  an  atom 
of  alkaline  metal,  or  of  an  ammonium  group,  for  the  remaining  basic 
hydrogen. 

Ammonium-Magnesium  Phosphate — Triple  phosphate — Mg- 
(NH4)P04+6Aq— 137+108 — is  produced  when  an  alkaline  phos- 
phate and  NH4OH  are  added  to  a  solution  containing  Mg.  When 
heated  it  is  converted  into  magnesium  pyrophosphate,  Mg2P207,  in 
which  form  H3P04  and  Mg  are  usually  weighed  in  quantitative 
analysis. 

Carbonates. — Magnesium  Carbonate — Normal  Magnesium  car- 
bonate— MgC03 — 84 — exists  native  in  magnesite,  and,  combined  with 
CaC03,  in  dolomite.  It  cannot  be  formed,  like  other  carbonates,  by 
decomposing  a  Mg  salt  with  an  alkaline  carbonate,  but  may  be  ob- 
tained by  passing  C02  through  H20  holding  tetramagnesic  tricar- 
bonate  in  suspension. 

Tetramagnesic  Tricarbonate — Magnesia  alba — Magnesii  carbo- 
nas  (U.  S.  P.)—  3MgC03.Mg(OH)2+4Aq— 310+72— occurs  in  com- 
merce in  light,  white  cubes,  composed  of  a  powder  which  is  amor- 
phous, or  partly  crystalline.  It  is  prepared  by  precipitating  a  solu- 
tion of  MgS04  with  one  of  Na2C03 : 

4MgS04+4Na2C03+5H20=4Na2S04+C02+3MgC03.Mg(OH)24H20 

If  the  precipitation  occurs  in  cold,  dilute  solutions,  very  little 
C02  is  given  off;  a  light,  bulky  precipitate  falls  (the  light  carbonate), 
and  the  solution  contains  magnesium,  probably  in  the  form  of  the 
bicarbonate  Mg(HC03)2.  This  solution,  on  standing,  deposits  crys- 
tals of  the  carbonate,  MgC03+3Aq.  If  hot  concentrated  solutions  ;nv 
used,  and  the  liquid  is  then  boiled  upon  the  precipitate,  C02  is  given 
off,  and  a  denser,  heavier  precipitate  (the  heavy  carbonate)  is  formed, 
which  varies  in  composition,  according  to  the  length  of  time  during 
which  the  boiling  is  continued,  and  to  the  presence  or  absence  of 
excess  of  sodium  carbonate.  The  pharmaceutical  product  is  a  mix- 
ture of  magnesium  carbonate  and  magnesium  hydroxide. 


ZINC  175 

Analytical  Characters. —  (1)  Ammonium  hydroxide:  voluminous, 
white  ppt.  from  neutral  solutions.  (2)  Potash  or  soda:  voluminous 
white  ppt.  from  warm  solutions,  prevented  by  the  presence  of  NH4 
salts,  and  of  certain  organic  substances.  (3)  Ammonium  carbonate: 
slight  ppt.  from  hot  solutions;  prevented  by  the  presence  of  NH4 
salts.  (4)  Sodium  or  potassium  carbonate :  white  ppt.,  best  from  hot 
solution;  prevented  by  the  presence  of  NH4  compounds.  (5)  Disodic 
phosphate:  white  ppt.  in  hot,  not  too  dilute  solutions.  (6)  Oxalic 
acid :  nothing  alone,  but  in  presence  of  NH4OH,  a  white  ppt. ;  not 
formed  in  presence  of  salts  of  NH4. 

ZINC. 

Sym'bol=Zii — Atomic  weight=65 — (International  =  65.37) — Mo- 
lecular weight— 65— Sp.  #r.=6.862-7.215. 

Occurs  principally  in  calamine  (ZnC03)  ;  and  Uende  (ZnS)  ;  also 
as  oxide  and  silicate;  never  free.  It  is  separated  from  its  ores  by 
calcining,  roasting,  and  distillation. 

It  is  a  bluish-white  metal ;  crystalline,  granular,  or  fibrous ;  quite 
malleable  and  ductile  when  pure.  The  commercial  metal  is  usually 
brittle.  At  130°-150°  it  is  pliable,  and  becomes  brittle  again  above 
200°-210°. 

At  500°  it  burns  in  air,  with  a  greenish-white  flame,  and  gives  off 
snowy-white  flakes  of  the  oxide.  In  moist  air  it  becomes  coated  with  a 
film  of  zinc  oxide  and  carbonate.  It  decomposes  steam  when  heated. 

Pure  H2S04  and  pure  Zn  do  not  react  together  in  the  cold.  If  the 
acid  is  diluted,  however,  it  dissolves  the  Zn,  with  evolution  of  H, 
and  formation  of  ZnS04,  in  the  presence  of  a  trace  of  Pt  or  Cu.  The 
commercial  metal  dissolves  readily  in  dilute  H2S04,  with  evolution  of 
H,  and  formation  of  ZnS04,  the  action  being  accelerated  in  presence 
of  Pt,  Cu,  or  As.  Zinc  surfaces,  thoroughly  coated  with  a  layer  of 
an  amalgam  of  Hg  and  Zn,  are  only  attacked  by  H2S04  if  they  form 
part  of  closed  galvanic  circuit;  hence  the  zincs  of  galvanic  batteries 
are  protected  by  amalgamation.  Zinc  also  decomposes  HN03,  HC1, 
and  acetic  acid.  Zinc  dissolves  in  strong  solutions  of  the  caustic 
alkalies  with  evolution  of  hydrogen  and  formation  of  double  oxides 
(zincates)  :  Zn+2KOH=Zn2K2+H2.  It  also  decomposes  many 
metallic  salts  in  solution  with  deposition  of  the  metal. 

When  required  for  toxicological  analysis,  zinc  must  be  perfectly 
free  from  As,  and  sometimes  from  P.  It  is  better  to  test  samples 
until  a  pure  one  is  found,  than  to  attempt  the  purification  of  a  con- 
taminated metal. 

Zinc  surfaces  are  readily  attacked  by  weak  organic  acids.  Vessels 
of  galvanized  iron  or  sheet  zinc  should  therefore  never  be  used  to  con- 
tain articles  of  food  or  medicines. 


176  TEXT-BOOK   OF   CHEMISTRY 

Zinc  Oxide — Zinci  oxidum  (U.  S.  P.) — ZnO — 81 — is  prepared 
either  by  calcining  the  precipitated  carbonate,  or  by  burning  Zn 
in  a  current  of  air.  An  impure  oxide,  known  as  tutty,  is  deposited 
in  the  flues  of  zinc  furnaces,  and  in  those  in  which  brass  is  fused. 
When  obtained  by  calcination  of  the  carbonate,  it  forms  a  soft,  white, 
tasteless,  and  odorless  powder.  When  produced  by  burning  the 
metal,  it  occurs  in  light,  voluminous,  white  masses.  It  is  neither 
fusible,  volatile,  nor  decomposable  by  heat,  and  is  completely  in- 
soluble in  neutral  solvents.  It  dissolves  in  dilute  acids,  with  forma- 
tion of  the  corresponding  salts. 

It  is  used  in  the  arts  as  a  white  pigment  in  place  of  lead  car- 
bonate, and  is  not  darkened  by  H2S. 

Zinc  Hydroxide— Zn( OH) 2—99— is  not  formed  by  union  of  ZnO 
and  H20 ;  but  is  produced  when  a  solution  of  a  Zn  salt  is  treated 
with  KOH.  Freshly  prepared,  it  is  very  soluble  in  alkalies,  and  in 
solutions  of  NH4  salts. 

Zinc  Chloride — Butter  of  zinc — Zinci  chloridum  (U.  S.  P.)  — 
ZnCl2+Aq— 136+18— is  obtained  by  dissolving  Zn  in  HC1,  or  by 
heating  Zn  in  Cl.  It  is  a  soft,  white,  very  deliquescent,  fusible,  vola- 
tile mass;  very  soluble  in  H20,  somewhat  less  so  in  alcohol.  Its 
solution  has  a  burning,  metallic  taste;  destroys  vegetable  tissues;. dis- 
solves silk ;  and  exerts  a  strong  dehydrating  action  upon  organic  sub- 
stances in  general. 

In  dilute  solution  it  is  used  as  a  disinfectant  and  antiseptic  (Bur- 
nett's fluid),  as  a  preservative  of  wood  and  as  an  embalming  injection. 

Liquor  zinci  chloridi  (U.  S.  P.)  is  an  aqueous  solution  of  zinc 
chloride  containing  not  less  than  48.5  per  cent,  nor  more  than  52 
per  cent,  of  ZnCl2. 

Zinc  Sulphate— White  vitriol— Zinci  sulphas  (U.  S.  P.)— ZnS04 
+7Aq— 161+126— is  formed  when  Zn,  ZnO,  ZnS,  or  ZnC03  is  dis- 
solved in  diluted  H2S04 : 

Zn+H2S04+zH20=:rH20+H2+ZnS04 

It  crystallizes  below  30°  with  7  Aq;  at  30°  with  6  Aq;  between 
40  °-50  °  with  5  Aq ;  at  0  °  from  concentrated  acid  solution  with  4  Aq. 
From  a  boiling  solution  it  is  precipitated  by  concentrated  H2S04  with 
2  Aq;  from  a  saturated  solution  at  100°  with  1  Aq;  and  anhydrous, 
when  the  salt  with  1  Aq  is  heated  to  238°. 

The  salt  usually  met  with  is  that  with  7  Aq,  which  is  in  large, 
colorless,  four-sided  prisms;  efflorescent;  very  soluble  in  H20,  spar- 
ingly soluble  in  weak  alcohol.  Its  solutions  have  a  strong,  styptic 
taste :  coagulate  albumen  when  added  in  moderate  quantity,  the  coag- 
ulum  dissolving  in  an  excess;  and  form  insoluble  precipitates  with 
the  tannins. 

Carbonates. — Zinc  Carbonate — ZnC03 — 125 — occurs  in  nature  as 
calamine.  If  an  alkaline  carbonate  is  added  to  a  solution  of  a  Zn 


CADMIUM  177 

salt,  the  neutral  carbonate,  as  in  the  case  of  Mg,  is  not  formed,  but 
an  oxycarbonate,  ttZnC03,  ?iZn(OH)2,  whose  composition  varies  with 
the  conditions  under  which  it  is  formed. 

Analytical  Characters. —  (1)  K,  Na  or  NH4  hydroxide:  white  ppt., 
soluble  in  excess.  (2)  Carbonate  of  K  or  Na:  white  ppt.,  in  absence 
of  NH4  salts.  (3)  Hydrogen  sulphide,  in  neutral  solution:  white  ppt. 
In  presence  of  an  excess  of  a  mineral  acid,  the  formation  of  this  ppt. 
is  prevented,  unless  sodium  acetate  is  also  present.  (4)  Ammonium 
sulphydrate:  white  ppt.,  insoluble  in  excess,  in  KOH,  NH4OH,  or 
acetic  acid;  soluble  in  dilute  mineral  acids.  (5)  Ammonium  car- 
bonate: white  ppt.,  soluble  in  excess.  (6)  Disodic  phosphate,  in 
absence  of  NH4  salts:  white  ppt.,  soluble  in  acids  or  alkalies.  (7) 
Potassium  ferrocyanide :  white  ppt.,  insoluble  in  HC1. 

Action  on  the  Economy — All  the  compounds  of  Zn  which  are  soluble  in 
the  digestive  fluids  behave  as  true  poisons;  and  solutions  of  the  chloride  (in 
common  use  by  tinsmiths,  and  in  disinfecting  fluids)  has  also  well-marked  cor- 
rosive properties.  When  Zn  compounds  are  taken,  it  is  almost  invariably  by 
mistake  for  other  substances:  the  sulphate  for  Epsom  salt,  and  solutions  of  the 
chloride  for  various  liquids,  such  as  gin,  fluid  magnesia,  vinegar,  etc. 

Metallic  zinc  is  dissolved  by  solutions  containing  NaCl,  or  organic  acids, 
for  which  reason  articles  of  food  kept  in  vessels  of  galvanized  iron  become  con- 
taminated with  zinc  compounds,  and,  if  eaten,  produce  more  or  less  intense 
symptoms  of  intoxication.  For  the  same  reason  materials  intended  for  analysis 
in  cases  of  supposed  poisoning,  should  never  be  packed  in  jars  closed  by  zinc 
caps. 

CADMIUM. 

Sym~bol=:Cd — Atomic  weight=1.12 — (International :112.40) — Mo- 
lecular weigJit—l\2—8p.  #r.=8.604. 

A  white  metal,  malleable  and  ductile  at  low  temperature,  brittle 
when  heated ;  which  accompanies  Zn  in  certain  of  its  ores.  It  resem- 
bles zinc  in  its  physical  as  well  as  its  chemical  characters.  It  is  used 
in  certain  fusible  alloys,  and  its  iodide  is  used  in  photography. 

Analytical  Characters. — Hydrogen  sulphide:  bright  yellow  ppt.; 
insoluble  in  NH4HS,  and  in  dilute  acids  and  alkalies,  soluble  in  boil- 
ing HN03  or  HC1. 


V.    ALUMINIUM  GROUP. 
GLUCINUM— ALUMINIUM— SCANDIUM— GALLIUM— INDIUM. 

The  existence  of  the  aluminates,  such  as  K2A1204,  would  seem  to 
place  aluminium  in  the  amphoteric  class.  These  compounds,  which 
are  formed  by  the  reactions:  A1(OH)3+KOH=KA1(X+2H20,  and 
Al2-f2KOH-f-2H20=2KA102+3H2,  are  double  oxides  rather  than 
salts.  They  resemble  the  zincates  and  what  has  been  said  concerning 
those  compounds  (see  p.  175)  applies  also  to  the  aluminates. 


178  TEXT-BOOK   OF   CHEMISTRY 


ALUMINIUM. 

Symbol^Al — Atomic  weight=21 — (International=27.1) — Molecu- 
lar weight— 54^- Sp.  gr.— 2.56-2.61. 

Occurrence. — Never  found  in  the  free  state,  but  abundant  in  the 
clays  as  silicate.  Also  in  feldspar,  mica,  and  garnet,  topaz,  and 
emerald.  As  a  fluoride  in  cryolite,  and  as  a  hydroxide  in  bauxite. 

Preparation. —  (1)  By  decomposing  vapor  of  aluminium  chloride 
by  Na  or  K  (Wohler).  (2)  Aluminium  hydroxide,  mixed  with  sodium 
chloride  and  charcoal,  is  heated  in  Cl,  by  which  a  double  chloride  of 
Na  and  Al  (NaAlClJ  is  formed.  This  is  then  heated  with  Na, 
when  Al  and  NaCl  are  produced.  (3)  These  ''chemical  methods" 
have  been  replaced,  in  the  industrial  preparation  of  aluminium,  by 
the  electrolytic  method,  in  which  a  mixture  of  cryolite  and  bauxite 
is  treated  in  an  electric  furnace. 

Properties. — Physical. — A  bluish-white  metal;  hard;  quite  mal- 
leable, and  ductile,  when  annealed  from  time  to  time;  slightly  mag- 
netic; a  good  conductor  of  electricity;  non- volatile ;  very  light,  and 
exceedingly  sonorous. 

Chemical. — It  is  not  affected  by  air  or  0,  except  at  very  high  tem- 
peratures, and  then  only  superficially.  If,  however,  it  contains  Si,  it 
burns  readily  in  air,  forming  aluminium  silicate.  It  does  not  decom- 
pose H20  at  a  red  heat ;  but  in  contact  with  Cu,  Pt,  or  I,  it  does  so 
at  100°.  It  combines  directly  with  B,  Si,  Cl,  Br,  and  I.  It  is 
attacked  by  HC1,  gaseous  or  in  solution,  with  evolution  of  H,  and 
formation  of  A1C13.  It  dissolves  in  alkaline  solutions,  with  forma- 
tion of  aluminates,  and  liberation  of  H.  It  alloys  with  Cu  to  form  a 
golden  yellow  metal  (aluminium  bronze). 

Aluminium  Oxide — Alumina — A1203 — 102 — occurs  in  nature, 
nearly  pure,  as  corundum,  emery,  ruby,  sapphire,  and  topaz;  and  is 
formed  artificially,  by  calcining  the  hydrate,  or  ammonium  alum,  at 
a  red  heat: 

2  Al  ( OH )  3— 3H20+ A1203 
Al,  (S04)  3.  (NH4)  2S04=  (NH4)  2S04+3S03+ A1203 

It  is  a  light,  white,  odorless,  tasteless  powder;  fuses  with  diffi- 
culty; and,  on  cooling,  solidifies  in  very  hard  crystals.  Unless  it 
has  been  heated  to  bright  redness,  it  combines  with  H20,  with  eleva- 
tion of  temperature.  It  is  almost  insoluble  in  acids  and  alkalies. 
H2S04,  diluted  with  an  equal  bulk  of  H20,  dissolves  it  slowly  as 
(A12)(S04)3.  Fused  potash  and  soda  combine  with  it  to  form  alu- 
minates. It  is  not  reduced  by  charcoal. 

Aluminium  Hydroxide — Aluminium  hydrate — Alumini  hydroxi- 
dum— (U.  S.  P.)— A1(OH)3— 78— is  formed  when  a  solution  of  alu- 


ALUMINIUM  179 

minium"  salt  is  decomposed  by  an  alkali,  or  alkaline  carbonate.  It 
constitutes  a  gelatinous  mass,  which,  when  dried,  leaves  an  amorphous, 
translucid  mass;  and,  when  pulverized,  a  white,  tasteless,  amorphous 
powder.  When  the  liquid  in  which  it  is  formed  contains  coloring 
matters,  these  are  carried  down  with  it,  and  the  dried  deposits  are 
used  as  pigments,  called  lakes.  It  is  used  as  a  mordant. 

When  freshly  precipitated,  it  is  insoluble  in  H20 ;  soluble  in 
acids,  and  in  solutions  of  the  fixed  alkalies.  When  dried  at  a  tem- 
perature above  50°,  or  after  24  hours'  contact  with  the  mother 
liquor,  its  solubility  is  greatly  diminished.  With  acids  it  forms  salts 
of  aluminium;  and  with  alkalies,  aluminates  of  the  alkaline  metal. 
Heated  to  near  redness,  it  is  decomposed  into  A1203,  and  H20.  A 
soluble  modification  is  obtained  by  dialyzing  a  solution  of  A1(OH)3 
in  A1C13,  or  by  heating  a  dilute  solution  of  aluminium  acetate  for 
24  hours. 

Aluminium  Chloride — A1C13 — 133.5 — is  prepared  by  passing  Cl 
over  a  mixture  of  A1203  and  C,  heated  to  redness,  or  by  heating  clay 
in  a  mixture  of  gaseous  HC1  and  vapor  of  CS2. 

It  crystallizes  in  colorless,  hexagonal  prisms;  fusible;  volatile; 
deliquescent;  very  soluble  in  H20  and  in  alcohol.  From  a  hot,  con- 
centrated solution,  it  separates  in  prisms  with  12Aq. 

The  disinfectant  called  chloralum  is  a  solution  of  impure  A1C13. 

Aluminium  Sulphate— Al2(SOJ3+18Aq— 342+324— is  obtained 
by  dissolving  A1(OH)3,  in  H2S04  or  (industrially)  by  heating  clay 
with  H2S04. 

It  crystallizes,  with  difficulty,  in  thin,  flexible  plates;  soluble  in 
H20 ;  very  sparingly  soluble  in  alcohol.  Heated,  it  fuses  in  its  Aq, 
which  it  gradually  loses  up  to  200°,  when  a  white,  amorphous  pow- 
der, A12(S04)3,  remains:  this  is  decomposed  at  a  red  heat,  leaving 
a  residue  of  pure  alumina. 

Alums — are  double  sulphates  of  an  univalent,  alkaline,  metal, 
and  trivalent  metal  (Fe,  Mn,  Cr,  or  Al).  When  crystallized,  they 
have  the  general  formula:  MiMiii(S04)2+12Aq.  They  are  isomor- 
phous  with  each  other. 

Alum — Alumen  (U.  S.  P.) — The  official  alum  is  the  ammonium 
alum  (ammonium  aluminium  sulphate)  NH4.Al(S04)2+12Aq — 237+ 
216,  or  the  potassium  alum  (potassium  aluminium  sulphate)  K.A1- 
(SOJ  2+12Aq— 258+216. 

It  is  formed  when  solutions  of  the  sulphates  are  mixed  in  suitable 
proportions.  It  crystallizes  in  large,  transparent,  regular  octa- 
hedra;  has  a  sweetish,  astringent  taste,  -and  is  readily  soluble  in 
H20. 

Dried  alum,  burnt  alum=alumen  exsiccatum  (U.  S.  P.)  is  an- 
hydrous— A1.NH4.(S04)2  or  A1.K(S04)2;  and  is  alum  from  which  the 
water  of  crystallization  has  been  driven  out  by  heat.  It  is  a  white 
powder,  readily  soluble  in  boiling  water,  but  slowly  soluble  in  cold 


180  TEXT-BOOK   OF   CHEMISTRY 

water.     Alum  is  used  in  dyeing,  and  in  purification  of  water  by 
precipitation. 

Silicates — are  very  abundant  in  the  different  varieties  of  clay,  feldspar, 
albite,  labradorite,  mica,  etc.  The  clays  are  hydrated  aluminium  silicates,  more 
or  less  contaminated  with  alkaline  and  oarthy  salts  and  iron,  to  which  last 
certain  clays  owe  their  color.  The  purest  is  kaolin,  or  porcelain  clay,  a  white 
or  grayish  powder.  They  are  largely  used  in  the  manufacture  of  the  different 
varieties  of  bricks,  terra  cotta,  pottery,  and  porcelain.  Porcelain  is  made  from 
the  purer  clays,  mixed  with  sand  and  feldspar;  the  former  to  prevent  shrinkage, 
the  latter  to  bring  the  mixture  into  partial  fusion,  and  to  render  the  product 
translucent.  The  fashioned  articles  are  subjected  to  a  first  baking.  The  porous, 
baked  clay  is  then  coated  with  a  glaze,  usually  composed  of  oxide  of  lead,  sand, 
and  salt.  During  a  second  baking  the  glaze  fuses,  and  coats  the  article  with  a 
hard,  impermeable  layer.  The  coarser  articles  of  pottery  are  glazed  by  throwing 
sodium  chloride  into  the  fire;  the  salt  is  volatilized,  and  on  contact  with  the 
hot  aluminium  silicate,  deposits  a  coating  of  the  fusible  sodium  silicate,  which 
hardens  on  cooling. 

Analytical  Characters. —  (1)  Potash,  or  soda:  white  ppt.,  soluble 
in  excess.  (2)  Ammonium  hydroxide:  white  ppt.,  almost  insoluble  in 
excess,  especially  in  presence  of  ammoniacal  salts.  (3')  Sodium  phos- 
phate: white  ppt.,  readily  soluble  in  KOH  and  NaOH,  but  not  in 
NH4OH;  soluble  in  mineral  acids,  but  not  in  acetic  acid.  (4)  Blow- 
pipe— on  charcoal  does  not  fuse,  and  moistened  with  cobalt  nitrate 
solution  turns  dark  sky-blue. 


VI.    NICKEL  GROUP. 
NICKEL—  COBALT. 

These  two  elements  bear  some  resemblance  chemically  to  those  of 
the  Fe  group;  from  which  they  differ  in  forming,  so  far  as  known, 
no  compounds  similar  to  the  ferrates,  chromates,  and  manganates. 
They  are  often  associated  with  iron,  and,  like  iron,  are  attracted 
by  the  magnet. 

NICKEL. 

=Ni  —  Atomic  weight  =  58  —  (International  —  58.68)  —  Sp. 


Occurs  in  combination  with  S,  and  with  S  and  As. 

It  is  a  white  metal,  hard,  slightly  magnetic,  not  tarnished  in  air. 
German  silver  is  an  alloy  of  Ni,  Cu,  and  Zn.  Nickel  is  now  exten- 
sively used  for  plating  upon  other  metals,  and  for  the  manufacture 
of  dishes,  etc.,  for  use  in  the  laboratory.  Its  salts  are  green. 

Nickelous  Sulphate  —  NiS04  —  is  obtained  by  dissolving  the  metal, 
hydroxide  or  carbonate  in  ILSO4.  It  forms  green  crystals  with  7  Aq, 


COBALT — COPPER  181 

and  combines  with  (NH4)2S04  to  form  a  double  sulphate,  used  in  the 
nickel-plating  bath,  for  which  use  it  must  be  free  from  K  or  Na. 

Analytical  Characters. —  (1)  Ammonium  sulphydrate:  black  ppt. ; 
insoluble  in  excess.  (2)  Potash  or  soda:  apple-green  ppt.,  in  ab- 
sence of  tartaric  acid;  insoluble  in  excess.  (3)  Ammonium  hydrate: 
apple-green  ppt. ;  soluble  in  excess ;  forming  a  violet  solution,  which 
deposits  the  apple-green  hydrate,  when  heated  with  KOH. 

COBALT. 

Symbol— Co — Atomic  weight  =  59 — (International  =  58.97) — Sp. 
0r.=8.5-8.7. 

Occurs  in  combination  with  As  and  S.  Its  salts  are  red  when 
hydrated,  and  usually  blue  when  anhydrous.  Its  phosphate  is  used 
as  a  blue  pigment. 

Analytical  Characters. — (1)  Ammonium  sulphydrate:  black  ppt.; 
insoluble  in  excess.  (2)  Potash:  blue  ppt.;  turns  red,  slowly  in  the 
cold,  quickly  when  heated ;  not  formed  in  the  cold  in  the  presence  of 
NH4  salts.  ( 3 )  Ammonium  hydroxide :  blue  ppt. ;  turns  red  in  ab- 
sence of  air,  green  in  its  presence. 


VII.     COPPER  GROUP. 
COPPER— MERCURY. 

Each  of  these  elements  forms  two  series  of  compounds.  One 
is  univalent,  Cu'  or  Hg',  and  is  distinguished  by  the  termination  ous ; 
the  other  is  bivalent,  Cu"  or  Hg",  and  is  designated  by  the  termina- 
tion ic.  Some  writers  double  the  formula?  of  the  ous  salts,  but  the 
more  modern  practice  is  to  write  HgCl  and  not  Hg2Cl2,  etc. 

COPPER. 

Symbol=Cu  (Cuprum) — Atomic  weight—^ — (International  = 
63.57)— Molecular  weight— 127— Sp.  #r.=8.914-8.952. 

Occurrence. — It  is  found  free,  in  crystals  or  amorphous  masses, 
sometimes  of  great  size ;  also  as  sulphide,  copper  pyrites;  oxide,  ruby 
ore  and  black  oxide;  and  basic  carbonate,  malachite,  a  mixed  car- 
bonate and  hydroxide  of  copper,  CuC03.Cu(OH)2. 

Properties. — Physical. — A  yellowish-red  metal;  dark-brown  when 
finely  divided;  very  malleable,  ductile,  and  tenacious;  a  good  con- 
ductor of  heat  and  electricity;  has  a  peculiar,  metallic  taste,  and  a 
characteristic  odor. 

Chemical. — It  is  unaltered  in  dry  air  at  the  ordinary  temperature ; 
but,  when  heated  to  redness,  is  oxidized  to  CuO.  In  damp  air  it 


182  TEXT-BOOK   OF    CHEMISTRY 

becomes  coated  with  a  brownish  film  of  oxide;  a  green  film  of  basic 
carbonate;  or,  in  salt  air,  a  green  film  of  basic  chloride.  Hot  H.,S04 
dissolves  it  with  formation  of  CuS04  and  SO.,.  It  is  dissolved  by 
HN03  with  formation  of  Cu(NO,)L>  and  NO;  and  by  IIC1  with  libera- 
tion of  H.  Weak  acids  form  with  it  soluble  salts,  in  presence  of  air 
and  moisture.  It  is  dissolved  by  NH4OH,  in  presence  of  air,  with 
formation  of  a  blue  solution.  It  combines  directly  with  Cl,  fre- 
quently with  light. 

Oxides. — Cuprous  Oxide — red  oxide  of  copper — Cu20 — 143 — is 
formed  by  calcining  a  mixture  of  CuCl  and  Na2C03;  or  a  mixture 
of  CuO  and  Cu.  It  is  a  red  or  yellow  powder;  permanent  in  air; 
sp.  gr.  5.749-6.093 ;  fuses  at  a  red  heat ;  easily  reduced  by  C  or  H. 
Heated  in  air  it  is  converted  into  CuO. 

Cupric  Oxide — Black  oxide  of  copper — CuO — 79 — is  prepared  by 
heating  Cu  to  dull  redness  in  air;  or  by  calcining  Cu(N03)2;  or  by 
prolonged  boiling  of  the  liquid  over  a  precipitate,  produced  by  heat- 
ing a  solution  of  a  cupric  salt,  in  presence  of  glucose,  with  KOH. 
By  the  last  method  it  is  sometimes  produced  in  Trommer's  test  for 
glucose,  when  an  excessive  quantity  of  CuS04  has  been  used. 

It  is  a  black,  or  dark  reddish-brown,  amorphous  solid;  readily 
reduced  by  C,  H,  Na,  or  K  at  comparatively  low  temperatures.  When 
heated  with  organic  substances,  it  gives  up  its  0,  converting  the  C 
into  C02,  and  the  H  into  H20 : 

C2H60+6CuO=6Cu+2C02+3H20 

a  property  which  renders  it  valuable  in  organic  analysis,  as  by  heat- 
ing a  known  weight  of  organic  substances  with  CuO,  and  weighing 
the  amount  of  C02  and  H20  produced,  the  percentage  of  C  and  H 
may  be  obtained.  It  dissolves  in  acids  with  formation  of  salts. 

Hydroxides — Cuprous  Hydroxide — CuOH — 80 — is  formed  as  a 
yellow  or  red  powder  when  mixed  solutions  of  CuS04  and  KOH  are 
heated  in  presence  of  glucose.  By  boiling  the  solution  it  is  rapidly 
dehydrated  with  formation  of  Cu20. 

Cupric  Hydroxide — Cu(OH)2 — 97 — is  formed  by  the  action  of 
KOH  upon  solution  of  CuS04,  in  absence  of  reducing  agents  and  in 
the  cold.  It  is  a  bluish,  amorphous  powder;  very  unstable,  and 
readily  dehydrated,  with  formation  of  CuO. 

Chlorides.— Cuprous  Chloride— CuCl — 98.5 — is  prepared  by  heating  Cu 
with  one  of  the  chlorides  of  Hg;  by  dissolving  Cu20  in  HC1.  without  contact 
of  air;  or  by  the  action  of  reducing  agents  on  solutions  of  CuCl2.  It  is  a 
heavy,  white  powder;  turns  violet  and  blue  by  exposure  to  light:  soluble  in 
HC1;  insoluble  in  H2O.  It  forms  a  crystallizable  compound  with  CO;  and  its 
solution  in  HC1  is  used  in  analysis  to  absorb  that  gas. 

Cupric  Chloride — CuCl2 — 134 — is  formed  by  dissolving  Cu  in  aqua  regia. 
If  the  Cu  is  in  excess,  it  reduces  CuCl2  to  CuCl.  It  eryst  all  i/.es  in  bluish-green, 
rhombic  prisms  with  2  Aq;  deliquescent  ;  very  soluble  in  H,O  and  in  alcohol. 

Cupric    Nitrate— C  u  (No,  I. — 187— is    formed    by    dissolving    Cu,    CuO.    or 


COPPER  183 

CuC03  in  HN03.  It  crystallizes'  at  20°-25°  with  3  Aq;  below  20°  with  6  Aq, 
forming  .blue,  deliquescent  needles.  Strongly  heated,  it  is  converted  into  CuO. 

Cupric  Sulphate — Blue  vitriol — Bluestone — Cupri  sulphas  (U. 
S.  P.)— CuS04-f-5Aq— 159+90— is  prepared:  (1)  by  roasting  CuS; 
(2)  from  the  water  of  copper  mines;  (3)  by  exposing  Cu,  moistened 
with  dilute  H2S04,  to  air;  (4)  by  heating  Cu  with  H2S04. 

As  ordinarily  crystallized,  it  is  in  fine,  blue,  oblique  prisms ;  solu- 
ble in  H20 ;  insoluble  in  alcohol ;  efflorescent  in  dry  air  at  15  °,  losing 
2  Aq.  At  100°  it  still  retains  1  Aq,  which  it  loses  at  230°,  leaving 
a  white,  amorphous  powder  of  the  anhydrous  salt,  which,  on  taking 
up  H20,  resumes  its  blue  color.  Its  solutions  are  blue,  acid,  styptic, 
and  metallic  in  taste. 

When  NH4OH  is  added  to  a  solution  of  CuS04,  a  bluish-white 
precipitate  falls,  which  redissolves  in  excess  of  the  alkali,  to  form  a 
deep  blue  solution.  Strong  alcohol  floated  over  the  surface  of  this 
solution  separates  long,  right  rhombic  prisms,  having  the  composition 
CuS04,4NH3-f-H20,  which  are  very  soluble  in  H2O.  This  solution 
constitutes  ammonio-sulphate  of  copper  or  aqua  sapphirina. 

Cupric  Arsenite — Scheele's  green — Mineral  green — is  a  mixture  of  cupric 
arsenite,  HCuAs03,  and  hydroxide;  prepared  by  adding  potassium  arsenite  to 
solution  of  CuSO4.  It  is  a  grass-green  powder,  insoluble  in  H20;  soluble  in 
NH4OH,  or  in  acids.  Exceedingly  poisonous. 

Schweinfurt  Green — Mitis  green  or  Paris  green — is  the  most  frequently 
used,  and  the  most  dangerous  of  the  cupro-arsenical  pigments.  It  is  prepared 
by  adding  a  thin  paste  of  neutral  cupric  acetate  with  H20  to  a  boiling  solution 
of  arsenous  acid,  and  continuing  the  boiling  during  a  further  addition  of  acetic 
acid.  It  is  an  insoluble,  green,  crystalline  powder,  having  the  composition 
(C2H302)2Cu-f3Cu(As02)2,  and  is  therefore  cupric  aceto-metarsenite.  It  is  de- 
composed by  prolonged  boiling  in  H20,  by  aqueous  solutions  of  the  alkalies,  and 
by  the  mineral  acids. 

Acetates.— Cupric  Acetate — Cu  ( C2H3O2 )  2-|-Aq—  181-J-18 — is  formed  when 
CuO  or  verdigris  is  dissolved  in  acetic  acid;  or  by  decomposition  of  a  solution 
of  CuS04  by  Pb(C2H3O2),.  It  crystallizes  in  large,  bluish-green  prisms,  which 
lose  their  Aq  at  140°.  At  240°-260°  they  are  decomposed  with  liberation  of 
glacial  acetic  acid. 

Basic  Acetates. — Verdigris — is  a  substance  prepared  by  exposing  to  air 
piles  composed  of  alternate  layers  of  grape-skins  and  plates  of  copper,  and 
removing  the  bluish-green  coating  from  the  copper.  It  is  a  mixture,  in 
varying  proportions,  of  three  different  substances:  ( C2H302 )  2Cu  ( OH ) -f-5Aq ; 
[(C2H302)2Cu]2,  Cu(OH)2-f5Aq;  and  ( C2H302 )  2Cu,2  ( CuH202 ) . 

Analytical  Characters. — CUPROUS — are  very  unstable  and  readily 
converted  into  cupric  compounds.  (1)  Potash:  white  ppt. ;  turning 
brownish.  (2)  Ammonium  hydroxide,  in  absence  of  air:  a  colorless 
liquid ;  turns  blue  in  air. 

CUPRIC — are  white  when  anhydrous;  when  soluble  in  H20  they 
form  blue  or  green,  acid  solutions.  (1)  Hydrogen  sulphide:  black 
ppt. ;  insoluble  in  KHS  or  NaHS ;  sparingly  soluble  in  NH4HS ;  solu- 
ble in  hot  concentrated  HN03  and  in  KCN.  (2)  Alkaline  sulphy- 
drates:  same  as  H2S.  (3)  Potash,  or  soda:  pale  blue  ppt.;  insoluble 


184  TEXT-BOOK   OF   CHEMISTRY 

in  excess.  If  the  solution  be  heated  over  the  ppt.,  the  latter  contracts 
and  turns  black.  (4)  Ammonium  hydroxide,  in  small  quantity: 
pale  blue  ppt. ;  in  larger  quantity:  deep  blue  solution.  (5)  Potassium 
or  sodium  carbonate:  greenish-blue  ppt.;  insoluble  in  excess;  turn- 
ing black  when  the  liquid  is  boiled.  (6)  Ammonium  carbonate:  pale 
blue  ppt.;  soluble  with  deep-blue  color  in  excess.  (7)  Potassium 
cyanide:  greenish-yellow  ppt.;  soluble  in  excess.  (8)  Potassium  fer- 
rocyanide :  chestnut-brown  ppt. ;  insoluble  in  weak  acids ;  decolorized 
by  KOH.  (9)  Iron  is  coated  with  metallic  Cu. 

Action  on  the  Economy. — Certain  of  the  copper  compounds,  such  as  the 
sulphate,  having  a  tendency  to  combine  with  protein  and  other  animal  sub- 
stances, produce  symptoms  of  irritation  by  their  direct  local  action,  when 
brought  in  contact  with  the  gastric  or  intestinal  mucous  membrane.  A  char- 
acteristic symptom  of  such  irritation  is  the  vomiting  of  a  greenish  matter,  which 
develops  a  blue  color  upon  the  addition  of  NH4OH. 

Severe  illness,  and  even  death,  has  followed  the  use  of  food  which  lias 
been  in  contact  with  imperfectly  tinned  copper  vessels.  It  is  probable  that 
the  poisonous  action  attributed  to  copper  is  sometimes  due  to  other  substances. 
The  tin  and  solder  used  in  the  manufacture  of  copper  utensils  contain  lead, 
and  in  some  cases  of  so-called  copper-poisoning,  the  symptoms  have  been  such  as 
are  as  consistent  with  lead-poisoning  as-  with  copper-poisoning.  Copper  is  also 
notoriously  liable  to  contamination  with  arsenic,  and  it  is  by  no  means  im- 
probable that  compounds  of  that  element  are  the  active  poisonous  agents  in 
some  cases  of  supposed  copper-intoxication.  Nor  is  it  improbable  that  articles 
of  food  allowed  to  remain  exposed  to  air  in  copper  vessels  should  undergo  those 
peculiar  changes  which  result  in  the  formation  of  poisonous  substances,  such  as 
the  sausage-  or  cheese-poisons,  or  the  ptomaines. 

The  treatment,  when  irritant  copper  compounds  have  been  taken,  should 
consist  in  the  administration  of  white  of  egg  or  of  milk,  with  whose  proteins  an 
inert  compound  is  formed  by  the  copper  salt.  If  vomiting  does  not  occur  spon- 
taneously, it  should  be  induced  by  the  usual  methods. 

The  detection  of  copper  in  the  viscera  after  death  is  not  without  interest, 
especially  if  arsenic  has  been  found,  in  which  case  its  discovery  or  non-discovery 
enables  us  to  differentiate  between  poisoning  by  the  arsenical  greens,  and  that 
by  other  arsenical  compounds.  The  detection  of  mere  traces  of  copper  is  of 
no  significance,  because,  although  copper  is  not  a  physiological  constituent  of 
the  body,  it  is  almost  invariably  present,  having  been  taken  with  the  food. 

Pickles  and  canned  vegetables  are  sometimes  intentionally  greened  by  the 
addition  of  copper;  this  fraud  is  readily  detected  by  inserting  a  large  needle 
into  the  pickle  or  other  vegetable;  if  copper  is  present  the  steel  will  be  found  to 
be  coated  with  copper  after  half  an  hour's  contact. 

MERCURY. 

Symbol=Hg  (Hydrargyrum)— Atomic  weigJit—2QQ— (Interna- 
tional—200.6)— Molecular  weight=200—Sp.  gr.  of  liquid^ 13.596 ; 
of  vapor=6.91. 

Occurrence. — Chiefly  as  cinnabar  (HgS)  ;  also  in  small  quantity 
free  and  as  chloride. 

Preparation. — The   commercial   product   is   usually   obtained   by 


MERCURY  185 

simple  distillation  in  a  current  of  air:  HgS+02=Hg-f-S02.  If  re- 
quired-pure, it  must  be  freed  from  other  metals  by  distillation,  and 
agitation  of  the  redistilled  product  with  mercurous  nitrate  solution, 
solution  of  FeCl3,  or  dilute  HN03. 

Properties. — Physical. — A  bright  metallic  liquid,  commonly  known 
as  quicksilver;  volatile  at  all  temperatures.  Crystallizes  in  octahedra 
of  sp.  gr.  14.0.  When  pure,  it  rolls  over  a  smooth  surface  in  round 
drops.  The  formation  of  tear-shaped  drops  indicates  the  presence 
of  impurities. 

Chemical. — If  pure,  it  is  not  altered  by  air  at  the  ordinary  tem- 
perature, but,  if  contaminated  with  foreign  metals,  its  surface  be- 
comes dimmed.  Heated  in  air,  it  is  oxidized  superficially  to  HgO.  It 
does  not  decompose  H20.  It  combines  directly  with  Cl,  Br,  I,  and  S. 
It  alloys  readily  with  most  metals  to  form  amalgams.  It  amalga- 
mates with  Fe  and  Pt  with  difficulty.  Hot,  concentrated,  H2S04 
dissolves  it,  with  evolution  of  S02,  and  formation  of  HgS04.  It  dis- 
solves in  cold  HN03,  with  formation  of  a  nitrate. 

An  alloy  is  a  substance  composed  of  two  or  more  metals. 

An  amalgam  is  an  alloy  containing  mercury. 

Elementary  mercury  is  insoluble  in  H20,  and  probably  in  the 
digestive  liquids.  It  enters,  however,  into  the  formation  of  three 
medicinal  agents:  hydrargyrum  cum  creta  (U.  S.  P.),  containing  38 
per  cent,  of  Hg;  massa  hydrargyri  (U.  S.  P.),  containing  33  per 
cent,  of  Hg;  and  unguentum  hydrargyri  (U.  S.  P.),  all  of  which 
owe  their  efficacy,  not  to  the  metal  itself,  but  to  a  certain  proportion 
of  oxide,  produced  during  their  manufacture.  The  fact  that  blue 
mass  is  more  active  than  mercury  with  chalk  is  due  to  the  greater 
proportion  of  oxide  contained  in  the  former.  It  is  also  probable  that 
absorption  of  vapor  of  Hg  by  cutaneous  surfaces  is  attended  by  its 
conversion  into  HgCl2. 

Oxides. — Mercurous  Oxide — Black  oxide  of  mercury — Hg20 — 
416 — is  obtained  by  adding  a  solution  of  HgN03  to  an  excess  of 
solution  of  KOH.  It  is  a  brownish  black,  tasteless  powder;  very 
prone  to  decomposition  into  HgO  and  Hg.  It  is  converted  into 
HgCl  by  HC1;  and  by  other  acids  into  the  corresponding  mercurous 
salts. 

It  exists  in  black  wash,  obtained  by  mixing  together  calomel  and 
lime  water: 

2HgCl+Ca(OH)2=H20+CaCl2+Hg20 

Mercuric  Oxide — Yelloiv  oxide  of  mercury — Red  oxide  of  mercury 
—Hydrargyri  oxidum  flavum  (U.  S.  P.) — Hydrargyri  oxidum 
rubrum  (U.  S.  P.) — HgO — 216 — is  prepared  by  two  methods:  (1)  by 
calcining  Hg(N03)2,  as  long  as  brown  fumes  are  given  off  (Hydr. 
oxid.  rubr.}  : 

2Hg(N03)2=4N02+02+2HgO 


186  TEXT-BOOK   OF   CHEMISTRY 

or,    (2)    by   precipitating  a  solution   of  a   mercuric  salt  by   excess 
of  KOH  (Hydr.  oxid.  flavum]  : 

HgCl2+2KOH=2KCl+H20-fHgO 

The  products  obtained,  although  the  same  in  composition,  differ 
in  physical  characters  and  in  the  activity  of  their  chemical  actions. 
That  obtained  by  (1)  is  red  and  crystalline;  that  obtained  by  (2)  is 
yellow  and  amorphous.  The  latter  is  much  the  more  active  in  its 
chemical  and  medicinal  actions. 

It  is  very  sparingly  soluble  in  H20,  the  solution  having  an  alka- 
line reaction,  and  a  metallic  taste.  It  exists  both  in  solution  and 
in  suspension  in  yellow  wash,  prepared  by  the  action  of  Ca(OH)2 
on  mercuric  chloride: 

HgCl2+Ca(OH)2=H20+CaCl2+HgO. 

Exposed  to  light  and  air,  it  turns  black,  more  rapidly  in  presence 
of  organic  matter,  giving  off  0,  and  liberating  Hg:HgO=Hg-(-0. 
It  decomposes  the  chlorides  of  many  metallic  elements  in  solution, 
with  formation  of  a  metallic  oxide  and  mercuric  oxychloride. 

Chlorides. — Mercurous  Chloride — Protocliloride  or  mild  chloride 
of  mercury — Calomel — Hydrargyri  chloridum  mite  (U.  S.  P.)  — 
HgCl — 235.5 — is  obtained  by  heating  a  mixture  of  mercuric  sulphate, 
mercury,  and  sodium  chloride,  when  the  calomel  (which  volatilizes) 
is  condensed: 

Hg+HgS04+2NaCl=Nji2S04+2HgCl 

Calomel  is  also  formed  in  a  number  of  other  reactions:  (1)  By  the 
action  of  Cl  upon  excess  of  Hg.  (2)  By  the  action  of  Hg  upon 
FeCl3.  (3)  By  the  action  of  HC1,  or  of  a  chloride,  upon  Hg,0,  or 
upon  a  mercurous  salt.  (2)  By  the  action  of  reducing  agents,  in- 
cluding Hg,  upon  HgCl2. 

Calomel  crystallizes  in  nature,  and,  when  sublimed,  in  quadratic 
prisms.  When  precipitated  it  is  deposited  as  a  heavy,  amorphous, 
white  powder,  faintly  yellowish,  and  producing  a  yellowish  innrk 
when  rubbed  upon  a  dark  surface.  It  sublimes,  without  fusing,  be- 
tween 420°  and  500°,  is  insoluble  in  cold  H20  and  in  alcohol;  soluble 
in  boiling  H2O  to  the  extent  of  1  part  in  12,000.  When  boiled  with 
H20  for  some  time,  it  suffers  partial  decomposition,  Hg  is  deposited 
and  HgCl2  dissolves. 

Although  HgCl  is  insoluble  in  H20,  in  dilute  HC1  and  in  pepsin 
solution,  it  is  dissolved  at  the  body  temperature  in  an  aqueous  solu- 
tion of  pepsin  acidulated  with  HC1. 

When  exposed  to  light,  calomel  becomes  yellow,  then  gray,  owing 
to  partial  decomposition,  with  liberation  of  Hg  and  formation  of 
HgCl,:  2HgCl=Hg+HgCl.,.  It  is  converted  into  HgCL  by  Cl  or 
aqua  regia:  2HgCl+Cl2=2Hpr<'l.,.  In  the  presence  of  I  !..<)',  I  con- 
verts it  into  a  mixture  of  Hgci..  and  HgI2 :  2HgCl+I2=H>?Cl2+ 


MERCURY  187 

HgI2.  It  Is  also  converted  into  HgCl2  by  HC1  and  by  alkaline  chlor- 
ides: 2JIgCl=HgCl2-f  Hg.  This  change  occurs  in  the  stomach  when 
calomel  is  taken  internally,  and  that  to  such  an  extent  when  large 
quantities  of  NaCl  are  taken  with  the  food,  that  calomel  cannot  be 
used  in  naval  practice  as  it  may  be  with  patients  who  do  not  subsist 
upon  salt  provisions.  It  is  converted  by  KI  into  Hgl :  HgCl-f-KI 
=KCl-f-HgI ;  which  is  then  decomposed  by  excess  of  KI  into  Hg 
and  HgI2,  the  latter  dissolving:  2HgI=Hg-|-HgI2.  Solutions  of  the 
sulphates  of  Na,  K  and  NH4  dissolve  notable  quantities  of  HgCl.  The 
hydroxides  and  carbonates  of  K  and  Na  decompose  it  with  formation 
of  H20:  2HgCl+Na2C03=Hg204-C02+2NaCl;  and  the  Hg20  so 
formed  is  decomposed  into  HgO  and  Hg.  If  alkaline  chlorides 
are  present,  they  react  upon  the  HgO  so  produced  with  formation 
of  HgCl2. 

Mercuric  Chloride — Perchloride  or  bichloride  of  mercury — Cor- 
rosive sublimate — Hydrargyri  chloridum  corrosivum  (U.  S.  P)  ; 
— HgCl2 — 271 — is  prepared  by  heating  a  mixture  of  5  pts.  dry  HgS04 
with  5  pts.  dry  NaCl,  and  1  pt.  Mn02  in  a  glass  vessel  communicating 
with  a  condensing  chamber. 

It  crystallizes  by  sublimation  in  octahedra,  and  by  evaporation  of 
its  solutions  in  flattened,  right  rhombic  prisms;  fuses  at  265°,  and 
boils  at  about  295  ° ;  soluble  in  H20  and  in  alcohol ;  very  soluble  in 
hot  HC1,  the  solution  gelatinizing  on  cooling.  Its  solutions  have  a 
disagreeable,  acid,  styptic  taste,  and  are  highly  poisonous.  Although 
HgCL  is  heavier  than  water  (sp.  gr.=5.4)  when  the  crystalline 
powder  is  thrown  upon  water  a  portion  floats  for  some  time. 

It  is  easily  reduced  to  HgCl  and  Hg,  and  its  aqueous  solutions 
are  so  decomposed  when  exposed  to  light ;  a  change  which  is  retarded 
by  the  presence  of  NaCl.  Heated  with  Hg,  it  is  converted  into 
HgCl.  When  dry  HgCl2,  or  its  solution,  is  heated  with  Zn,  Cd, 
Ni,  Fe,  Pb,  Cu,  or  Bi,  those  elements  remove  part  or  all  of  its  Cl, 
with  separation  of  HgCl  or  Hg.  Its  solution  is  decomposed  by 
H2S,  with  separation  of  a  yellow  sulphochloride,  which,  with  an  ex- 
cess of  the  gas,  is  converted  into  black  HgS.  It  is  soluble  without  de- 
composition in  H2S04,  HN03,  and  HC1.  It  is  decomposed  by  KOH  or 
NaOH,  with  separation  of  a  brown  oxychloride  if  the  alkaline 
hydroxide  is  in  limited  quantity;  or  of  the  orange-colored  HgO  if  it 
is  in  excess.  A  similar  decomposition  is  effected  by  Ca(OH),  and 
Mg(OH)2;  which  does  not,  however,  take  place  in  presence  of  an 
alkaline  chloride,  or  of  certain  organic  matters,  such  as  sugar  and 
gum.  Many  organic  substances  decompose  it  into  HgCl  or  Hg, 
especially  under  the  influence  of  sunlight.  Thus  in  sunlight  it  is 
reduced  by  oxalic  acid,  which  is  itself  oxidized  to  carbon  dioxide : 
2HgCU+a04H,=2HgCl-h2C02+2HCl.  For  this  reason  it  behaves 
as  an"oxidant:~2HgCl2+H20=2HgCl+2HCl-fO.  Albumin  forms 
with  it  a  white  precipitate,  which  is  insoluble  in  H20,  but  soluble  in 


188  TEXT-BOOK   OF   CHEMISTRY 

an  excess  of  fluid  albumin  and  in  solutions  of  alkaline  chlorides.     It 
is  a  very  energetic  germicide. 

Mercurammonium  Chloride — White  precipitate — Ammoniated 
mercury — Hydrargyrum  ammoniatum  (U.  S.  P.) — NH2HgCl — 251.5 
—is  prepared  by  adding  a  slight  excess  of  NH4OH  to  a  solution  of 
HgCl2.  It  contains  79  per  cent,  of  Hg;  and  is  a  white  powder, 
insoluble  in  alcohol,  ether,  and  cold  H20 :  decomposed  by  hot  H20, 
with  separation  of  a  heavy,  yellow  powder.  It  is  entirely  volatile, 
without  fusion.  The  fusible  white  precipitate  is  formed  in  small 
crystals  when  a  solution  containing  equal  parts  of  HgCl2  and  NH4C1 
is  decomposed  by  Na2C03.  It  is  mercurdiammonium  chloride, 
NH2Hg,NH4Cl2. 

Iodides. — Mercurous  Iodide — Protoiodide  or  yellow  iodide — 
Hydrargyri  iodidum  flavum  (U.  S.  P.) — Hgl — 327 — is  prepared  by 
grinding  together  200  pts.  Hg  and  127  pts.  I  with  a  little  alcohol, 
until  a  green  paste  is  formed.  It  is  a  greenish-yellow,  amorphous 
powder,  insoluble  in  H20  and  in  alcohol.  When  heated,  it  turns 
brown,  and  volatilizes  completely.  When  exposed  to  light,  or  even 
after  a  time  in  the  dark,  it  is  decomposed  into  HgI2  and  Hg.  The 
same  decomposition  is  brought  about  instantly  by  KI ;  more  slowly 
by  solutions  of  alkaline  chlorides,  and  by  HC1  when  heated.  NH4OH 
dissolves  it  with  separation  of  a  gray  precipitate. 

Mercuric  Iodide — Biniodide  or  red  iodide — Hydrargyri  iodidum 
rubrum  (U.  S.  P.) — HgI2 — 454 — is  obtained  by  double  decomposition 
between  HgCL  and  KI,  care  being  had  to  avoid  too  great  an  excess  of 
the  alkaline  iodide,  that  the  soluble  potassium  iodhydrargyrate  may 
not  be  formed : 

HgCl2+2KI=2KCl+HgI2 

It  is  sparingly  soluble  in  H20 ;  but  forms  colorless  solutions  with 
alcohol.  It  dissolves  readily  in  many  dilute  acids,  and  in  solutions  of 
ammoniacal  salts,  alkaline  chlorides,  and  mercuric  salts;  and  in  solu- 
tions of  alkaline  iodides.  Iron  and  copper  convert  it  into  Hgl, 
then  into  Hg.  The  hydroxides  of  K  and  Na  decompose  it  into  oxide  or 
oxyiodides,  .and  combine  with  another  portion  to  form  iodhydrargy- 
rates,  which  dissolve.  NH4OH  separates  from  its  solution  a  brown 
powder,  and  forms  a  yellow  solution,  which  deposits  white  flocks. 

Mercuric  Cyanide — Hg(CN)2 — 252 — is  best  prepared  by  heat- 
ing together,  for  a  quarter  of  an  hour,  potassium  ferrocyanide,  1  pt. ; 
HgS04,  2  pts. ;  and  H20,  8  pts.  It  crystallizes  in  quadrangular 
prisms ;  soluble  in  8  pts.  of  H20,  much  less  soluble  in  alcohol ;  highly 
poisonous.  When  heated  dry  it  blackens,  and  is  decomposed  into 
(CN)2  and  Hg;  if  heated  in  presence  of  H20  it  yields  HCN,  Hg, 
C02,  and  NH3.  Hot  concentrated  H2S04,  and  HC1,  HBr,  HI,  and 
H2S  in  the  cold  decompose  it,  with  liberation  of  HCN.  It  is  not 
decomposed  by  alkalies. 


MERCURY  189 

Nitrates  —  Mercurous  Nitrate  —  HgN03  +  2 Aq  —  262  +36  —  is 
formed  when  excess  of  Hg  is  digested  with  moderately  diluted  HNO3 : 

3Hg+4HN03=:3HgN03+NO+2H20 

It  effloresces  in  air ;  fuses  at  70  ° ;  dissolves  in  a  small  quantity  of 
hot  H20,  but  with  a  larger  quantity  is  decomposed  with  separation 
of  the  yellow,  basic  trimercuric  nitrate,  Hg(N03)2,2HgO-f-Aq. 

Mercuric  Nitrate— Hg(N03)2— 324— is  formed  when  Hg  or  HgO 
is  dissolved  in  excess  of  HN03,  and  the  solution  evaporated  at  a 
gentle  heat: 

3Hg+8HN03=3Hg(NOs)  2+2NO+4H2O 

This  salt  is  soluble  in  H20,  and  exists  in  the  volumetric  standard 
solution  used  in  Liebig's  process  for  urea;  and  probably  in  citrine 
ointment='Unguentum  hydrarargyri  nitratis  (U.  S.  P.). 

Sulphates. — Mercurous  Sulphate — Hg2S04 — 496 — is  a  white, 
crystalline  powder,  formed  by  gently  heating  together  2  pts.  Hg  and 
3  pts.  H2S04,  and  causing  the  product  to  combine  with  2  pts.  Hg. 
Heated  with  NaCl  it  forms  HgCl. 

Mercuric  Sulphate — HgS04 — 296 — is  obtained  by  heating  to- 
gether Hg  and  H2S04,  or  Hg,  H2S04,  and  HN03.  It  is  a  white, 
crystalline,  anhydrous  powder,  which,  on  contact  with  H20,  is  de- 
composed with  formation  of  trimercuric  sulphate,  HgS04,  2HgO; 
a  yellow,  insoluble  powder,  known  as  turpeth  mineral. 

Analytical  Characters. — MERCUROUS. — (1)  Hydrochloric  acid: 
white  ppt. ;  insoluble  in  H20  and  in  acids ;  turns  black  with  NH4OH ; 
when  boiled  with  HC1,  deposits  Hg,  while  HgCL  dissolves.  (2)  Hy- 
drogen sulphide ;  black  ppt. ;  insoluble  in  alkaline  sulphydrates,  in 
dilute  acids,  and  in  KCN;  partly  soluble  in  boiling  HN03.  (3) 
Potash:  black  ppt.;  insoluble  in  excess.  (4)  Potassium  iodide:  green- 
ish ppt. ;  converted  by  excess  into  Hg,  which  is  deposited  and  HgI2, 
which  dissolves. 

MERCURIC. — (1)  Hydrogen  sulphide:  black  ppt.  If  the  reagent  is 
slowly  added,  the  ppt.  is  first  white,  then  orange,  finally  black.  (2) 
Ammonium  sulphydrate :  black  ppt. ;  insoluble  in  excess,  except  in 
the  presence  of  organic  matter.  (3)  Potash,  or  soda:  yellow  ppt.; 
insoluble  in  excess.  (4)  Ammonium  hydroxide:  white  ppt.;  soluble 
in  great  excess  and  in  solutions  of  NH4  salts.  (5)  Potassium  car- 
bonate: red  ppt.  (6)  Potassium  iodide:  yellow  ppt.,  rapidly  turning 
to  salmon  color,  then  to  red;  easily  soluble  in  excess  of  KI,  or  in 
great  excess  of  mercuric  salt.  (7)  Stannous  chloride,  in  small  quan- 
tity: white  ppt.;  in  larger  quantity:  gray  ppt.;  and  when  boiled: 
deposit  of  globules  of  Hg. 

Action  on  the  Economy. — Metallic  mercury  is  without  action  upon  the 
animal  economy.  On  contact,  however,  with  alkaline  chlorides  it  is  converted 
into  a  soluble  double  chloride,  and  this  the  more  readily  the  greater  the  degree 


190  TEXT-BOOK   OF   CHEMISTRY 

of  subdivision  of  the  metal.  The  mercurials  insoluble  in  dilute  HC1  are  also 
inert  until  they  are  converted  into  soluble  compounds. 

Mercuric  chloride,  a  substance  into  which  many  other  compounds  of  Hg 
are  converted,  when  taken  into  the  stomach  or  applied  to  the  skin,  not  only 
has  a  distinctly  corrosive  action,  by  virtue  of  its  tendency  to  unite  with  protein 
bodies,  but,  when  absorbed,  it  produces  well-marked  poisonous  effects,  somewhat 
similar  to  those  of  arsenical  poisoning.  Indeed,  owing  to  its  corrosive  action, 
and  to  its  greater  solubility  and  more  rapid  absorption,  it  is  a  more  dangerous 
poison  than  As3O3.  In  poisoning  by  HgCl2,  the  symptoms  begin  sooner  after 
the  ingestion  of  the  poison  than  in  arsenical  poisoning,  and  those  phenomena 
referable  to  the  local  action  of  the  toxic  are  more  intense.  But  the  entire 
duration  of  the  poisoning  is  greater.  In  fatal  cases,  death  usually  occurs  in 
5  to  12  days. 

The  treatment  should  consist  in  the  administration  of  white  of  egg,  not  in 
too  great  quantity,  and  the  removal  of  the  compound  formed,  by  emesis,  before 
it  has  had  time  to  redissolve  in  the  alkaline  chlorides  contained  in  the  stomach. 

Absorbed  Hg  tends  to  remain  in  the  system  in  combination  with  protein 
bodies,  from  which  it  may  be  set  free,  or,  more  properly,  brought  into  soluble 
combination,  at  a  period  quite  removed  from  the  date  of  last  administration,  by 
the  exhibition  of  alkaline  iodides. 

Mercury  is  eliminated  principally  by  the  saliva  and  urine,  in  which  it  may 
be  readily  detected.  The  fluid  is  faintly  acidulated  with  HC1,  and  in  it  is 
immersed  a  short  bar  of  Zn,  around  which  a  spiral  of  dentist's  gold  foil  is  wound 
in  such  a  way  as  to  expose  alternate  surfaces  of  Zn  and  Au.  After  24  hours,  if 
the  saliva  or  urine  contain  Hg,  the  Au  will  be  whitened  by  amalgamation;  and, 
if  dried  and  heated  in  the  closed  end  of  a  small  glass  tube,  will  give  off  Hg, 
which  condenses  in  globules,  visible  with  the  aid  of  a  magnifier,  in  the  cold 
part  of  the  tube. 


ORGANIC     CHEMISTRY 
COMPOUNDS  OF  CARBON. 

In  the  beginning  of  the  nineteenth  century  chemistry  was  divided 
into  the  two  sections  of  inorganic  and  organic.  The  former  treated 
of  the  products  of  the  mineral  world,  the  latter  of  substances  pro- 
duced in  organized  bodies,  vegetable  or  animal.  This  subdivision, 
originally  made  upon  the  supposition  that  organic  substances  could 
only  be  produced  by  "vital  processes,"  is  retained  only  for  con- 
venience and  because  of  the  great  number  of  the  carbon  compounds. 

When  it  was  found  that  organic  substances  were  made  up  of  a 
very  few  elements,  and  that  they  all  contained  carbon,  Gmelin  pro- 
posed to  consider  as  organic  substances  all  such  as  contained  more 
than  one  atom  of  C,  his  object  in  thus  limiting  the  minimum  number 
of  C  atoms  being  that  substances  containing  one  atom  of  C,  such  as 
carbon  dioxide  and  marsh  gas,  are  formed  in  the  mineral  kingdom, 
and  consequently,  according  to  then  existing  views,  could  not  be  con- 
sidered as  organic.  Such  a  distinction,  still  adhered  to  in  some  text- 
books, of  necessity  leads  to  most  incongruous  results.  Under  it  the 
first  terms  of  the  homologous  series  (see  p.  193)  of  saturated  hydro- 
carbons, CH4,  alcohol,  CH4O,  acids,  CH202,  and  all  their  derivatives 
are  classed  among  mineral  substances,  while  all  the  higher  terms  of 
the  same  series  are  organic.  Under  it  urea,  CON2H4,  the  chief  prod- 
uct of  excretion  of  the  animal  body,  is  a  mineral  substance,  but 
ethene,  C2H4,  obtained  from  the  distillation  of  coal,  is  organic. 

The  idea  of  organic  chemistry  conveyed  by  the  definition :  "  that 
branch  of  the  science  of  chemistry  which  treats  of  the  carbon  com- 
pounds containing  hydrogen,"  is  still  more  fantastic.  Under  it  hy- 
drocyanic acid,  CNH,  is  organic,  but  the  cyanides,  CNK,  are  min- 
eral. Oxalic  acid,  C204H2,  is  organic,  and  potassium  hydroxide, 
KOH,  unquestionably  mineral.  If  these  two  act  upon  each  other 
in  the  proportion  of  90  parts  of  the  former  to  56  of  the  latter,  the 
organic  monopotassic  oxalate,  C204HK,  is  formed,  but  if  the  pro- 
portion of  KOH  is  doubled,  other  conditions  remaining  the  same,  the 
mineral  dipotassic  oxalate,  C204K2,  is  produced.  Similarly  one  of 
the  sodium  carbonates,  Na2C08,  is  mineral;  the  other,  NaHC03,  is 
organic. 

The  notion  that  organic  substances  could  only  be  formed  by  some 
mysterious  agency,  manifested  only  in  organized  beings,  was  finally 
exploded  by  the  labors  of  Wohler  and  Kolbe.  The  former  obtained 
urea  from  ammonium  cyanate  (1828)  ;  while  the  latter,  at  a  subse- 
quent period,  formed  acetic  acid,  using  in  its  preparation  only  such 

191 


192  TEXT-BOOK   OF   CHEMISTRY 

unmistakably  mineral  substances  as  coal,  sulphur,  aqua  regia,  and 
water.  Since  Wohler's  first  synthesis,  chemists  have  succeeded  not 
only  in  making  from  mineral  materials  many  of  the  substances  pre- 
viously only  formed  in  the  laboratory  of  nature,  but  have  also  pro- 
duced a  vast  number  of  carbon  compounds  which  were  previously 
unknown,  and  which,  so  far  as  we  know,  have  no  existence  in 
nature. 

At  the  present  time,  therefore,  we  must  consider  as  an  organic 
substance  any  compound  containing  carbon,  whatever  may  be  its 
origin  and  whatever  its  properties. 

Organic  chemistry  is,  therefore,  simply  the  chemistry  of  the  car- 
bon compounds.  In  the  study  of  the  compounds  of  the  other  ele- 
ments, we  have  to  deal  with  a  small  number  of  substances,  relatively 
speaking,  formed  by  the  union  with  each  other  of  a  large  number  of 
elements.  With  the  organic  substances  the  reverse  is  the  case.  Al- 
though compounds  have  been  formed  which  contain  C  along  with 
each  of  the  other  elements,  the  great  majority  of  the  organic  sub- 
stances are  made  up  of  C,  combined  with  a  very  few  other  elements ; 
H,  0,  and  N  occurring  in  them  most  frequently. 

It  is  chiefly  in  the  study  of  the  carbon  compounds  that  we  have  to 
deal  with  radicals  (see  p.  45).  Among  mineral  substances  there 
are  many  whose  molecules  consist  simply  of  a  combination  of  two 
atoms.  Among  organic  substances  there  is  none  which  does  not 
contain  a  radical :  indeed,  organic  chemistry  has  been  defined  as  "  the 
chemistry  of  compound  radicals." 

The  atoms  of  carbon  possess  in  a  higher  degree  than  those  of  any 
other  element  the  power  of  uniting  with  each  other,  and  in  so  doing 
of  interchanging  valences.  Were  it  not  for  this  property  of  the  C 
atoms,  we  could  have  but  one  saturated  compound  of  carbon  and 
hydrogen,  CH4,  or  expressed  graphically: 


A 

There  exist,  however,  a  great  number  of  such  compounds,  which 
differ  from  each  other  by  one  atom  of  C  and  two  atoms  of  H.  In 
these  substances  the  atoms  of  C  may  be  considered  as  linked  together 
in  a  continuous  chain,  their  free  valences  being  satisfied  by  H  atoms, 
thus: 

H  H    H  H    H    H    H 

H— 0— H  H— C— C— H  H— C— C— C— C— H 


COMPOUNDS   OF   CARBON 


193 


Homologous  Series. — It  will  be  observed  that  these  formulas 
differ  jrom  each  other  by  CH2  or  some  multiple  of  CH2,  more  or  less. 
In  examining  numbers  of  organic  substances  which  are  closely  related 
to  each  other  in  their  properties,  we  find  that  we  can  arrange  the 
great  majority  of  them  in  series,  each  term  of  which  differs  from  the 
one  below  it  by  CH2;  such  a  series  is  called  an  homologous  series. 
It  will  be  readily  understood  that  such  an  arrangement  in  series  vastly 
facilitates  the  remembering  of  the  composition  of  organic  bodies.  In 
the  following  table,  for  example,  are  given  the  saturated  hydro- 
carbons, and  their  more  immediate  derivatives.  At  the  head  of  each 
vertical  column  is  an  algebraic  formula,  which  is  the  general  formula 
of  the  entire  series  below  it ;  n  being  equal  to  the  numerical  position 
in  the  series. 


HOMOLOGOUS  SERIES. 


Saturated  hy- 
drocarbons, 
C«H2n+2 

Alcohols, 
CnIl2n+2O 

Aldehydes 
CnH2nO 

Acids, 
CnH2nO2 

Ketones 
CnH2»O 

CH4 

CH40 

CH,0 

C02H2 

C2H6 

C2H60 

C2H40 

C202H4 

. 

C3H8 

C3H80 

C3H60 

C302H6 

C3H«0 

C4H10 

C4H100 

C4H80 

C402H8 

C4H80 

C5H12 

C5H120 

C5H100 

C502H10 

C8H100 

C6H140 

C6H120 

C602H12 

C£E£ 

C7H160 

C7H140 

C702H14 

, 

CSH18 

C8H180 

C8H160 

C802H18 

. 

C9H20 

C9H200 

C902H18 

, 

C10H22 

C10H22O 

C1002H20 

• 

CaH* 

'.    '.    '.    '. 

• 

C12O2H24 

; 

C13H28 

. 

. 

§ 

C14H30 

.... 

• 

C1402H28 

• 

But  the  arrangement  in  homologous  series  does  more  for  us  than 
this.  The  properties  of  substances  in  the  same  series  are  similar, 
or  vary  in  regular  gradation  according  to  their  position  in  the  series. 
Thus,  in  the  series  of  monoatomic  alcohols  (see  table  above)  each 
member  yields  on  oxidation,  first  an  aldehyde,  then  an  acid.  Each 
yields  a  series  of  compound  ethers  by  the  action  of  acids  upon  it. 
The  boiling-points  of  ethylic  alcohol  and  its  seven  superior  homologues 
are:  78.3°,  97.4°,  116.8°,  137°,  157°,  176°,  195°,  from  which  it  will 
be  seen  that  the  boiling-point  of  any  one  of  them  can  be  determined, 
with  a  maximum  error  of  less  than  1°,  by  taking  the  mean  of  those 
of  its  neighbors  above  and  below.  In  this  way  we  may  predict,  to 
some  extent,  the  properties  of  a  wanting  member  in  a  series  before  its 
discovery. 

The  terms  of  any  homologous  series  must  all  have  the  same  con- 


194  TEXT-BOOK   OF   CHEMISTRY 

stitution,  i.  c.,  their  constituent  atoms  must  be  similarly  arranged 
within  the  molecule.     (See  p.  46.) 

Isomerism — Metamerism— Polymerism. — Two  substances  are 
said  to  be  isomeric,  or  to  be  isomeres  of  each  other,  when  they  have 
the  same  percentage  composition.  If,  for  instance,  we  analyze  acetic 
acid,  formic  aldehyde  and  methyl  formate,  we  find  that  each  body 
consists  of  C,  0  and  H,  in  the  following  proportions: 

Carbon    40          =     12 

Oxygen     53.33     =     16 

Hydrogen     6.67     =       2 


100.00  30 

This  identity  of  percentage  composition  may  occur  in  two  ways. 
The  three  substances  may  each  contain  the  same  number  of  each  kind 
of  atom  in  a  molecule ;  or  they  may  contain  in  their  several  molecules 
the  same  kinds  of  atoms  in  multiple  proportions.  In  the  above  ex- 
ample each  substance  may  have  the  formula,  CH20 ;  or  one  may  have 
that  formula  and  the  others,  C2H402,  C3H003,  C4H804,  C5H1005,  etc. 

When  two  or  more  substances  have  the  same  percentage  com- 
position and  the  same  molecular  weight  they  are  said  to  be  meta- 
meric.  When  they  have  the  same  percentage  composition  and  their 
molecular  weights  are  simple  multiples  of  the  lowest  molecular 
weight  represented  by  that  percentage  composition,  they  are  said 
to  be  polymeric. 

Other  conditions  of  isomerism  will  be  considered  later  (see  space 
isomerism,  p.  238,  and  place  isomerism,  pp.  260,  337). 

In  order  to  determine  the  composition  (the  empirical  formula)  of 
an  organic  substance,  two  factors  are  therefore  necessary:  the  per- 
centage composition  and  the  molecular  weight. 

Elementary  Organic  Analysis. — The  first  step  in  an  analysis  to 
determine  the  composition  of  an  organic  substance  is  a  qualitative 
analysis  to  identify  the  elements  existing  in  the  molecule.  This 
having  been  done,  the  quantitative  analysis  is  next  in  order. 

The  simplest  case  is  where  the  substance  is  a  hydrocarbon,  i.e., 
a  compound  of  carbon  and  hydrogen  only.  The  determination  of 
both  elements  is  made  in  one  operation,  by  taking  advantage  of  the 
fact  that  when  a  compound  containing  carbon  and  hydrogen  is  heated 
with  cupric  oxide  all  the  carbon  is  converted  into  C02,  and  all  the 
hydrogen  into  H20.  Thus,  if  C2H60+ 6CuO=2C02-f  3H20+6Cu,  46 
parts  of  alcohol  will  produce  88  pts.  of  carbon  dioxide  and  54  pts.  of 
water. 

The  apparatus  required  consists  of  a  tube  of  difficultly  fusible  glass,  called  a 
combustion  tube,  about  60  cent,  long,  drawn  out  to  a  point  and  closed  at  one 
end,  a  "combustion  furnace,"  in  which  this  tube  may  be  heated,  and  tin- 
absorbing  apparatus  referred  to  below.  A  weighed  quantity  of  the  substance  of 


COMPOUNDS   OF   CARBON 


195 


which  a  "combustion"  is  to  be  made  (sealed  in  a  small  glass  bulb  if  liquid) 
is  placed  in  the  closed  end  of  the  combustion  tube,  a  Fig.  17,  along  with  the 
requisite  quantity  of  recently  ignited  cupric  oxide,  leaving  space  tor  the 
passage  of  the  gases  produced.  The  tube  is  then  placed  in  the  furnace  and  its 
open  end  connected  with  a  U  tube,  &,  filled  with  fused  CaCl2,  or  with  frag- 
ments of  pumice  moistened  with  concentrated  H2S04,  whose  weight  has  been 
determined,  and  whose  purpose  it  is  to  absorb  the  H20  produced.  This  first 
U  tube  is  connected  with  a  "Liebig's  bulb"  containing  a  strong  solution  of 
KOH,  c,  and  this  in  turn  with  another  U  tube  in  all  respects  similar  to  the 
first,  d,  both  c  and  d  having  been  previously  weighed.  The  purpose  of  c  is  to 
absorb  the  C02  produced,  that  of  d  to  retain  water  carried  over  from  c  by 
the  current  of  gas.  The  combustion  tube  is  then  carefully  heated  until  the 
evolution  of  gases  ceases,  when  the  closed,  drawn-out  end  of  the  tube  is  broken 
and  connected  with  a  gasometer  containing  pure,  dry  oxygen,  a  current  of 
which  is  passed  slowly  through  the  apparatus  to  bring  the  last  portions  of  the 
products  of  combustion  into  the  absorbing  apparatus.  Finally  the  U  tubes 
and  the  KOH  bulb  are  again  weighed.  The  increase  in  weight  of  6  is  the 


\ 


FIG.  17. 


weight  of  H2O  produced,  every  9  parts  of  which  represent  1  part  of  H.  The 
increase  in  weight  of  c  and  d  is  the  weight  of  CO2  produced,  every  44  parts 
of  which  represent  12  parts  of  C.  If  the  substance  analyzed  contains  N,  Cl,  Br 
or  I,  a  heated  column  of  pure  metallic  Cu  is  interposed  toward  the  open  end  of 
the  combustion  tube,  to  reduce  any  oxides  of  N  produced  to  N,  and  to  retain 
the  Cl,  Br  or  I.  If  the  substance  contains  S,  a  layer  of  lead  peroxide  is 
similarly  placed  to  retain  the  S  and  PbS04. 

If  the  substance  consists  of  C,  H  and  0,  the  C  and  H  are  determined  in 
the  manner  above  described,  and  the  difference  between  the  sum  of  their 
weights  and  that  of  the  substance  burnt  is  the  amount  of  O. 

Nitrogen  is  most  readily  determined  by  the  method  of  Kjeldahl.  A  known 
weight  of  the  substance  is  dissolved  by  heating  it  in  concentrated  H2S04. 
Potassium  permanganate  is  then  added  until  the  mixture  is  green.  The  N 
contained  in  the  substance  is  thus  converted  into  ammonia.  The  strongly  acid 
liquid  is  diluted,  rendered  alkaline  by  addition  of  NaOH,  and  the  NH3  is  dis- 
tilled over  into  a  receiver  containing  a  known  quantity  of  acid.  The  amount 
of  NH3  produced  is  calculated  from  the  amount  of  acid  neutralized,  and  every 
17  parts  of  NH3  represent  14  parts  of  N.  In  the  analysis  of  nitro-  and  cyano- 
gen compounds  sugar  is  added,  and  in  that  of  nitrates,  benzoic  acid. 


Determination  of  Molecular  Weights. — The  percentage  compo- 
sition having  been  determined,  the  simplest  corresponding  ratio  of  the 
atoms  in  the  molecule  is  obtained  by  dividing. the  percentage  of  each 
clement  by  its  atomic  weight.  Thus  if  analyses  are  made  of  formic 


196  TEXT-BOOK   OF   CHEMISTRY 

aldehyde,  acetic  acid,  methyl  formate,  lactic  acid  and  glucose,  the 
results  in  each  case  will  be: 

Carbon     40.00  per  cent.  -=-  12  =  3.33  =  1 

Hydrogen    6.67     "      "     -=-    1  =  6.67  =  2 

Oxygen    53.33     "      "     -f. 16  =  3.33  =  1 

and  the  simplest  empirical  formula  of  all  of  the  substances  mentioned 
is  therefore  CH20.  The  molecular  weight  of  formic  aldehyde  is  30; 
its  formula  is  therefore  CH20(  12+2+16).  The  molecular  weights 
of  acetic  acid  and  of  methyl  formate  are  60:  they,  therefore,  each 
have  the  formula  C2H402.  The  molecular  weight  of  lactic  acid  is  90 
and  that  of  glucose  180:  the  formula  of  the  former  is,  therefore, 
C3H603,  and  that  of  the  latter  C6H1206. 

If  the  substance  is  one  which  can  be  vaporized  without  decom- 
position, its  molecular  weight  is  derived  from  its  specific  gravity  as 
referred  to  hydrogen.  The  process  for  determining  the  specific 
gravity  now  generally  adopted  is  that  of  Victor  Meyer. 

Determination  of  Constitution. — The  identity  and  properties  of 
organic  compounds  depend  not  only  upon  their  composition,  i.e.,  the 
number  and  kind  of  atoms  composing  the  molecule,  but  also  upon 
their  constitution,  i.e.,  the  arrangement  of  the  atoms  in  the  molecule 
(see  p.  46).  The  constitution  of  a  substance  is  determined  by  a 
study  of  the  methods  of  its  formation,  of  the  products  of  its  decom- 
position, and  of  the  substances  produced  by  the  introduction  of  other 
elements  or  groups  into  its  molecule.  A  statement  of  the  more 
important  principles,  and  one  or  two  examples,  must  suffice  here,  the 
subject  being  further  developed  in  the  sequel. 

The  carbon  atom  is  quadrivalent  in  almost  all,  if  not  in  all  its 
compounds.  In  the  few  in  which  it  is  considered  as  bivalent,  as  in 
carbon  monoxide,  CO,  and  the  isonitrils,  (C2H5) — N=C,  the  oxygen 
may  be  considered  to  be  quadrivalent,  and  the  nitrogen  quinquiva- 
lent, in  which  case  the  carbon  would  be  quadrivalent. 

The  carbon  atoms  may  unite  with  each  other  in  three  ways: 
(1)  Two  carbon  atoms  may  exchange  a  single  valence  in  their  union, 
forming  a  hexavalent  group,  =  C — 0  =  ;  (2)  they  may  unite  with 
exchange  of  two  valences,  forming  a  quadrivalent  group,  z=C=C— ; 
or,  (3)  they  may  unite  with  exchange  of  three  valences,  forming  a 
bivalent  group,  — C  =  C — .  These  are  referred  to  as  single,  double 
and  treble  linkages,  respectively. 

Those  compounds  in  which  all  of  the  linkages  are  single,  and  in 
which  all  of  the  possible  valences  of  the  constituent  atoms  are  satisfied 
are  saturated  compounds.  No  other  atom  or  radical  can  be  intro- 
duced into  a  saturated  molecule  except  by  substitution,  i.e.,  by  caus- 
ing the  introduced  atom  or  radical  to  take  the  place  of  some  other, 
or  others,  of  cquivjilcnt  valence,  simultaneously  removed.  Thus,  when 
chloroform  (itself  a  substituted  di-rivntive  of  marsh  gas,  CHJ  is 


COMPOUNDS  OP   CARBON  197 

converted  into  carbon  tetrachloride,  the  remaining  hydrogen  is  re- 
moved as  hydrochloric  acid:  CHC13+C12=CC14+HC1. 

Only  such  substances  as  contain  two  carbon  atoms  doubly  or 
trebly  linked,  =C=C=  or  — C  =  C — ,  are  usually  considered  as 
unsaturated  compounds.  Such  compounds  may  be  modified  both  by 
substitution  and  by  addition,  i.  e.,  by  breaking  out  the  double  or 
treble  linkages  and  the  introduction  of  two  new  univalents,  or  one 
bivalent,  for  each  linkage  so  liberated.  Thus,  ethylene  yields  ethylene 
chloride  by  addition:  H2C:CH2+C12=C1H2C.CH2C1;  or,  by  substitu- 
tion and  addition,  carbon  hexachloride :  H2C  :CH2-|-5C12=C13C.CC13 
+4HC1. 

In  the  reactions  referred  to  above  in  which  chlorine  is  substituted 
for  hydrogen,  it  is  not  only  added  to  the  molecule  operated  upon,  but 
also  removes  hydrogen  by  combining  with  it,  and  hence  two  atoms  of 
chlorine  are  required  for  each  atom  of  hydrogen  removed.  Similarly, 
when  0  removes  H2,  in  oxidations,  two  atoms  of  oxygen  are  required 
for  each  two  atoms  of  hydrogen  removed,  as  when  alcohol  is  oxidized 
to  acetic  acid:  C2Hf)0+02=C2H402+H20.  Consequently  in  oxida- 
tions an  even  number  of  hydrogen  atoms  is  always  removed.  The 
tendency  to  the  formation  of  water  is  so  strong  that  in  reactions  in 
which  two  or  more  hydroxyl  groups  should  unite  with  the  same 
carbon  atom,  water  almost  invariably  splits  off  and  oxygen  unites 
doubly  with  the  carbon.  Thus  caustic  potash  does  not  act  upon 
ethidene  chloride  to  produce  a  glycol  according  to  the  equation : 
CH3.CHC12+2KOH=CH3CH  ( OH )  2+2KCl 

But  to  produce  an  aldehyde  according  to  the  equation: 
GH3.CHC12+2KOH=CH3CHO+H20+2KC1. 

Exceptions  to  this  rule  occur  when  the  carbon  atom  is  linked  to 
another  carbon  atom  contained  in  a  highly  oxidized  or  halide  group, 
as  in  the  compounds : 

COOH  CC18  COOH 

HJ,/OH  Hfl/OH  rl/OH 

LC\OH  HC\OH  |\OH 

COOH 
Glyoxalic   acid.  '       Chloral    hydrate.  Mesoxalic  acid. 

Usually  when  an  atom  or  group  replaces  another  in  a  compound 
it  occupies  the  position  vacated  by  that  which  is  removed,  as  when 
alcohol  is  formed  by  the  action  of  caustic  potash  upon  ethyl  iodide: 

CH3.CH2I+KOH=CH3.CH2OH+KL 

There  is  an  exception  to  this  rule  when  an  unsaturated  compound 
may  yield  either  another  unsaturated  compound  in  obedience  to  the 
rule  or  an  isomeric  saturated  compound  in  violation  of  it,  the  more 
stable  saturated  compound  is  formed.  Thus  the  hydration  of  vinyl 
bromide,  CH2  :CHBr,  does  not  produce  vinyl  alcohol,  CH2:CHOH, 
but  its  isomere :  aldehyde,  CH3CHO.  Indeed,  unsaturated  compounds 


198 


TEXT-BOOK   OF   CHEMISTRY 


are  frequently  converted  into  saturated  isomeres  by  intramolecular 
transposition  of  atoms  by  mere  application  of  heat. 

The  genesis  of  ethylic  alcohol  from  the  action  of  caustic  potasli 
upon  ethyl  iodide :  CH3CH2I+KOH=CH3.CH2OH+KI,  shows  that 
the  alcohol  contains  the  univalent  group  CH2OH,  or 

H         OH 

\c/ 

/C\ 
H 

which,  on  oxidation,  may  lose  two  atoms  of  hydrogen  with  formation 
of  either  one  of  the  two  univalent  groups  CHO,  or  COOH ; 


either  — C 


\ 


or  0=C<^ 


which  occur  in  the  products  of  oxidation  of  ethylic  alcohol :  aldehyde 
and  acetic  acid. 

The  groups  CH2OH,  CHO  and  COOH,  referred  to  above,  are  ex- 
amples of  the  so-called  characterizing  groups  which  exist  in  the 
molecules  of  different  classes  of  substances.  The  following  are  the 
more  commonly  recurring  characterizing  groups,  and  the  classes  of 
substances  in  which  they  occur: 

(CH2OH)'    =  HO/C\B     in  Primai7  alcohols,  called  methoxyl, 


(CHOH)"  =  HQ/C 

(COH)'"  =    ;C.OH 

(CHO)'  =0=C( 

(CO)"  =0:C: 

(COOH)'  =  O=- 


"  secondary  alcohols, 

"  tertiary  alcohols, 

"  aldehydes, 

"  ketones,  called  carlonyl,* 

"  acids,  called  carboxyl, 


(S02OH)'     =  °}}S/OH      "    sulphonic  acids, 

"    sulphones, 
"    amido    compounds, 
"    imido  compounds, 
"    nitro  compounds, 
"    nitroso  compounds. 

Nomenclature  of  Organic   Compounds. — The  vast  number  and 
great  variety  of  structure  of  organic  compounds  make  it  difficult  to 

*  Thin  A.TOIIP  also  exists   in  other  compound*,   as  In   the  aldehydes  and  acids  in  the  manner  in- 
dicated  in    the    text,    and    In   cuiii|M.mids.    such  as  carbonyl  chloride.   COCl...   urea,   N  H...CO.  M  I.,,   etc. 


(SO,)" 

_  v  \\  o_ 
~~O// 

(NH,)' 

=  Ha:N. 

(NH)" 

=  H.N: 

(NO,)' 

_o\\N 
~o//N 

(NO)' 

=  O:N. 

COMPOUNDS   OF   CARBON  199 

devise  a  system  of  nomenclature  which  will  apply  to  the  more  com- 
plex derivatives  without  producing  names  which  are  most  complicated 
and  difficult  of  pronunciation.  Indeed,  in  view  of  the  constantly 
increasing  number  of  carbon  compounds,  no  complete  system  of  no- 
menclature is  as  yet  possible.  The  most  recent  attempt  to  formulate 
one  is  that  of  the  Geneva  "Convention  of  1892.  In  this  system  the 
names  of  the  hydrocarbons  serve  as  the  roots  from  which  the  names 
of  their  derivatives  are  constructed  by  the  addition  of  syllables  indi- 
cating the  function  (see  p.  208)  of  the  substance.  Thus  the  alcohols 
are  indicated  by  the  syllable  ol,  the  aldehydes  by  al,  the  ketones  by  on, 
and  the  acids  by  the  word  acid.  The  * '  Geneva ' '  name  of  ethylic  alco- 
hol would  be  ethanol,  that  of  acetic  aldehyde  ethanal  and  that  of 
acetic  acid  etlian-acid.  These  names  have  not  come  into  general  use. 

In  the  nomenclature  generally  followed  the  name  of  a  substance 
is  made  up  of  the  name  of  that  of  the  class,  or  "function,"  to  which 
the  substance  belongs,  as  acid,  alcohol,  ketone,  ester,  etc.,  to  which 
is  added  a  qualifying  word  derived  from  the  origin  of  th-B  body,  as 
lactic  acid,  acetic  acid,  etc..  or  from  its  composition,  as  methylic  alco- 
hol, ethylic  ether,  etc.,  and  the  names  of  any  radicals  which  have  been 
introduced  into  the  molecule  of  the  parent  compound.  Thus  the 
name  of  the  substance  COOH.CH2(NH.CH3)  is  methyl-amido-acetic 
acid,  in  which  "acetic  acid"  indicates  that  it  is  derived  from  acetic 
acid,  COOH.CH3,  the  syllable  amido  that  NH2  has  been  substituted 
for  H  in  the  CH3  of  the  acid,  and  methyl  that  CH3  has  been  substi- 
tuted for  H  in  NH2. 

The  names  of  the  univalent  radicals  terminate  in  yl,  as  methyl 
(CH8)',  ethyl  (C2H5)',  acetyl  (C2H30)',  etc.  Those  of  bivalent  radi- 
cals terminate  in  ene,  as  methylene,  (CH2)",  ethidene  (C2H4)",  etc., 
and  those  of  the  trivalent  radicals  in  enyl,  or  in  ine,  as  methenyl  or 
methine  (CH)'",  ethemjl  or  ethine  (C2H8)'",  etc. 

Classification  of  the  Carbon  Compounds. — The  hydrocarbons, 
consisting  of  carbon  and  hydrogen  only,  constitute  the  framework  of 
the  classification  adopted,  all  other  carbon  compounds  being  con- 
sidered as  derivable  from  the  hydrocarbons  by  substitution  or  by 
addition. 

Carbon  compounds  are  divided  into  two  great  classes,  differen- 
tiated by  the  manner  in  which  the  carbon  atoms  are  linked  together : 

A.  OPEN  CHAIN  COMPOUNDS,  also  called  acyclic,  fatty,  or  aliphatic 
compounds.  In  these  compounds  the  carbon  atoms  are  attached  to 
each  other  in  an  open  or  arborescent  chain,  in  which  two  or  more 
carbon  atoms  are  linked  to  but  one  other  carbon  atom,  as  in  the 
compounds : 

H    H    H    H    H   H 

/CH2.CH8 
H— C— C— C— C— C— C— H  CH3.CH2.CH 

I      I      I      I      I      I  \CH. 

H    H    H    H   H    H 


200  TEXT-BOOK   OF   CHEMISTRY 

In  the  hydrocarbons  of  this  class  the  number  of  hydrogen  atoms, 
or  this  number,  plus 'the  number  of  univalent  atoms  that  can  be  in- 
troduced into  the  molecule  by  addition,  is  equal  to  twice  the  number 
of  carbon  atoms  plus  two. 

B.  CLOSED  CHAIN  COMPOUNDS,  also  called  cyclic  or  aromatic  com- 
pounds. These  compounds  contain  one  or  more  closed  chains,  rings, 
or  nuclei  in  which  each  carbon  atom  is  linked  to  at  least  two  other 
carbon  atoms,  or  their  equivalent,  as  in  the  compounds: 

H  H,  H       H 

A  J  ^    i 

//\  /\  /\\   /\\ 

H— C        C— H          H2=C        C=H2  H— C        C        C— H 

I    H     H    H 

H— C         C— H          H2=C         C— C— C— C— H          H— C         C         C— H 

\\/  \/\  i  i  r  \//  \// 

C  NHHHH  CO 

i  I  I.I 

I'  11  -tl  XI 

Benzene.  Coniine  Naphthalene. 

The  closed  chain  compounds  are  subdivided  into  two  classes : 

I.  Carbocyclic  compounds,  in  which  the  ring  or  rings  consist  of 
carbon  atoms  exclusively,  as  in  benzene  and  naphthalene,  and 

II.  Heterocyclic  compounds,  in  which  atoms  of  elements  other 
than  carbon  enter  into  the  composition  of  the  ring,  as  in  confine. 


OPEN  CHAIN,  ALIPHATIC,  ACYCLIC  OR  FATTY 
COMPOUNDS. 

HYDROCARBONS. 

Six  series  are  known : 

A.  Methane,    or    Paraffin    Series.      These    are    saturated    com- 
pounds and  have  the  algebraic  formula,  CnH2n+2.     Their  names  ter- 
minate in  "ane,"  e.g.,  Butane,  CH3.CH2CH2.CH3. 

B.  Olefine   Series,  containing  two  doubly-linked  carbon  atoms. 
General   formula   CnH2n.     Their  names   terminate   in   "ene,"   e.g., 
Butene,  CH2:CH.CH2CH3. 

C.  Acetylene  Series,  containing  two  trebly-linked  carbon  atoms. 
Algebraic  formula,  CnH2«-2.     Their  names  terminate  in  "ine,"  e.g., 
Propine,  CH!C.CH3. 

D.  Diolefine  Series,  containing  two  pairs  of  doubly-linked  car- 
bon atoms.    Algebraic  formula,  CnH2«-2,  isomeric  with  the  members 
of  the  acetylene  series.     Their  names  terminate  in   "diene,"   e.g., 
Propadiene,  CH2  :C  :CH2.     Trienes  are  also  known,  containing  three 
pairs    of    doubly-linked    carbon    atoms,    e.g.,    Octatriene,    CH2:CH.- 
CH2.CH2.CH  :CH.CH  :CH2. 

E.  Olefine-acetylene  Series,  containing  both  doubly-  and  trebly- 
linked  carbon  atoms.     General  formula,  CnH2n-4.     Their  names  ter- 
minate in  "one,"  e.g.,  Butone,  H2C:CH.CiCH. 

F.  Diacetylene    Series,    containing   two    pairs    of    trebly-linked 
carbon  atoms.     Algebraic  formula,  CnH2«-6.     Their  names  are  con- 
structed by  prefixing  the  syllable  "di"  to  the  name  of  the  hydrocar- 
bon of  series  C,  from  which  they  are  derivable  by  fusion  and  elimi- 
nation of  H2  or  its  equivalent,  e.g.,  Diacetylene,  HCiC.CiCH.     The 
sixth    terms,     of    which    there     are    two     isomeres:     Dipropargyl, 
HC.:C.CH2.CH2.CiCH,  and  Dimethyl  diacetylene,  H3C.CiC.C;C.CH3, 
are  isomeric  with  benzene,  the  most  important  of  the  closed  chain 
hydrocarbons. 

SATURATED  COMPOUNDS— METHANE  SERIES. 

The  hydrocarbons  of  the  methane  series  are  saturated,  as  are  also 
most  of  the  compounds  derived  from  them.  There  are,  however, 
certain  of  their  derivatives,  classed  here  for  convenience,  which  con- 
tain either  a  doubly-linked  oxygen  atom  (the  aldehydes  and  ketones) 
or  a  trivalent  nitrogen  atom  (the  amines,  amides,  etc.),  which  form 
addition  products  and  are,  therefore,  strictly  speaking,  unsaturated 
compounds. 

201 


202  TEXT-BOOK   OF   CHEMISTRY 


HYDROCARBONS. 

The  saturated  hydrocarbons  at  present  known  extend  in  unbroken 
series  from  methane,  CH4,  to  tetracosane,  C24H50;  and  above  that 
some  members  are  known  as  high  as  dimyricyl,  C60H122.  The  alge- 
braic formula  of  the  series  is  CnH2n+2.  They  are  called  paraffins 
because  of  their  great  stability  (parum=\itt\e,  aj^nw^affinity)  ;  and 
also  alkanes.  They  are  also  considered  as  the  hydrides  of  the  alco- 
holic radicals,  CnEbn+i,  methyl,  ethyl,  etc.,  which  are  called  alkyls. 

In  the  higher  terms  of  the  series,  above  the  third,  there  exist  two 
or  more  isomeres,  increasing  progressively  in  number  with  an  in- 
creasing number  of  carbon  atoms.  Thus  there  are  three  having  the 
empirical  formula,  C5H12: 

(1)  CH8.CH2.CH2.CH2.CH8,  (3)   CH3\ 

(2)  CH8\f,HrH  rH  ,  CH3— C.CH,. 
CH3/ CH-CH"CH»>                   and'  CH3/ 

Hydrocarbons  and  their  derivatives  having  the  "unbranched" 
structure  shown  in  formula  (1)  above,  are  designated  as  normal 
compounds;  those  derived  from  (2)  are  called  iso  compounds;  and 
those  derived  from  (3)  meso  compounds. 

The  number  of  possible  isomeres  increases  rapidly  with  an  in- 
creasing number  of  carbon  atoms.  It  has  been  calculated  that  the 
number  of  possible  isomeres  with  increasing  values  of  n  are  as 
follows : 

n  =  1         n  =  2         n  =  3          n  =  4          n  =  5  n  =  6 

111235 

n  =  7         n  =  S         n  =  9         n  =  10         n=ll         n=12 
9  18  35  75  159  357 

Many  of  these  hydrocarbons  exist  in  nature,  in  petroleum,  and  in 
the  gases  accompanying  it.  They  may  be  produced  by  the  follow- 
ing general  reactions: 

(1)  By  the  action  of  finely-divided  zinc,  silver  or  copper,  or  of 
sodium  either  alone,  at  elevated  temperatures,  or  in  the  presence  of 
H20,  upon  the  corresponding  iodides: 

2C2H5I+Zn2+2H20=ZnH202+ZnI2+2C2HG,   or, 
2C2H5I+Na2=2NaI+C4H10 

(2)  By  electrolysis  of  the  corresponding  fatty  acid: 

2C2H402=2C02+H2+C2H6 

(3)  By  heating  the  salts  of  the  fatty  acids  with  soda-lime: 

CH3.COONa-fNaOH=Na2C03+CH4 

(4)  By  the  action  of  the  organo-zincic  derivative  upon  the  iodide 
of  the  alcoholic  radical,  or  upon  the  corresponding  define  iodide. 


HYDROCARBONS  203 

(5)  By  the  action  of  highly  concentrated  hydriodic  acid  at  275°- 
300°  upon  hydrocarbons  of  the  ethene  and  ethine  series,  upon  alco- 
hols, amines,  etc.     This  is  a  method  of  hydrogenation  applicable  in 
many  other  cases. 

(6)  By  the  action  of  alkyl  magnesium  halides  upon  ammonia, 
amines,  or  phenylhydrazine : 

NH3+R.MgX=H2N.MgX+RH 

(7)  By  the  destructive  distillation  of  many  organic  substances. 
General  Properties. — They  are  gaseous,  liquid,  or  solid,  and  have 

sp.  gr.  and  boiling  points  increasing  with  the  number  of  C  atoms. 
The  first  four  members  are  gaseous  at  the  ordinary  temperature,  those 
above  C15H32  are  crystalline  solids;  the  intermediate  ones  are  color- 
less liquids.  They  are  lighter  than  H2O,  neutral,  insoluble  in  H20, 
soluble  in  alcohol,  ether,  and  in  liquid  hydrocarbons.  Their  odor  is 
faint  and  not  unpleasant. 

Chlorine  and  bromine  decempose  them,  with  formation  of  products 
of  substitution.  They  are  inflammable  and  burn  with  a  luminous 
flame.  Nitric  acid  forms  nitro-derivatives  with  the  higher  terms. 

Methyl  Hydride— Methane — Marsh-gas — Fire-damp — CH4 — 16— 
is  given  off  in  swamps  as  a  product  of  decomposition  of  vegetable 
matter,  in  coal  mines,  and  in  the  gases  issuing  from  the  earth  in  the 
vicinity  of  petroleum  deposits.  It  is  also  formed  during  putrefac- 
tion of  protein  bodies  and  fermentation  of  carbohydrates.  From 
these  origins  it  exists  in  intestinal  gases,  sometimes  to  the  extent  of 
26.5  per  cent.  Coal-gas  contains  it  in  the  proportion  of  36-50  per 
cent. 

Preparation. — It  may  be  prepared  by  strongly  heating  a  mixture 
of  sodium  acetate  with  sodium  hydroxide  and  quick-lime: 

NaC2H302+NaOH:=Na2C03+CH4 

Its  complete  synthesis,  which  is  of  theoretic  interest,  may  be 
effected  in  several  ways:  (IX  Carbon  disulphide  is  first  produced  by 
passing  vapor  of  sulphur  over  coal,  heated  to  redness:  C+S2=CS2. 
This  may  either  be  passed,  along  with  hydrogen  sulphide,  over  red- 
hot  copper,  when:  CS2+2H2S+8Cu=CH4+4Cu2S,  or,  (2)  it  may  be 
converted  into  carbon  tetrachloride  by  the  reaction:  CS2+3C12=: 
CC14+S2C12 ;  and  this  reduced  by  nascent  hydrogen :  CCl4-]-4H2=: 
CH4+4HC1.  (3)  Carbon  monoxide,  prepared  by  heating  carbon  in  a 
limited  quantity  of  air,  is  reduced  by  hydrogen  when  the  two  are 
treated  with  the  induced  electric  current:  CO-|-3H2=CH4-fH20. 
(4)  Aluminium  carbide  is  decomposed  by  water  according  to  the 
equation :  C3A1^+12H20=:3CH44-2A12  ( HO )  8. 

Properties. — It  is  a  colorless,  odorless,  tasteless  gas;  very  spar- 
ingly soluble  in  H2O ;  sp.  gr.  0.559A.  At  high  temperatures,  it  is 
decomposed  into  C  and  H.  It  burns  in  air  with  a  pale  yellow  flame. 
Mixed  with  air  or  0  it  explodes  violently  on  contact  with  flame,  pro- 


204  TEXT-BOOK   OF   CHEMISTRY 

ducing  water  and  carbon  dioxide;  the  latter  constituting  the  after- 
damp of  miners.  It  is  not  affected  by  Cl  in  the  dark,  but,  under 
the  influence  of  diffuse  daylight,  one  or  more  of  the  H  atoms  are 
displaced  by  an  equivalent  quantity  of  Cl.  In  direct  sunlight  the 
substitution  is  accompanied  by  an  explosion. 

Petroleum. — Crude  petroleum  varies  in  color  from  a  faintly  yellowish 
tinge  to  a  dark  brown,  nearly  black,  with  greenish  reflections.  The  lighter- 
colored  varieties  are  limpid,  and  the  more  highly  colored  of  the  consistency  of 
thin -syrup.  The  sp.  gr.  varies  from  0.74  to  0.92.  Crude  petroleums  consist 
of  normal  paraffins  (the  lowest  terms  of  the  series  being  found  in  the  gases 
accompanying  petroleum  and  held  in  solution  by  the  oil  under  the  pressure 
it  supports  in  natural  pockets),  besides  hydrocarbons  of  the  olefine,  paraffin, 
and  benzene  series.  They  also  contain  varying  quantities  of  sulphur  com- 
pounds, which  communicate  a  disgusting  odor  to  some  oils. 

The  crude  oil  is  highly  inflammable,  usually  highly  colored,  and  is  pre- 
pared for  its  multitudinous  uses  in  the  arts  by  the  processes  of  distillation  and 
refining.  The  products  of  lowest  boiling  point  are  usually  consumed,  but  are 
sometimes  condensed. 

The  principal  products  of  petroleum  are:  Cymogene,  boils  at  0°,  used  in 
ice  machines;  Rhigolene,  a  highly  inflammable  liquid,  sp.  gr.  about  0.60,  boils 
at  about  20°,  used  to  produce  cold  by  its  rapid  evaporation.  Petroleum  ether, 
boils  at  40°-50°,  used  as  a  solvent.  Gasolene,  boils  from  45°  to  76°,  used  as  a  fuel 
and  for  the  manufacture  of  "air  gas."  Naphtha,  divided  into  three  grades,  C, 
B,  and  A,  boils  from  82.2°  to  148.8°,  used  as  a  solvent  for  fats,  etc.,  and  in 
the  manufacture  of  "water  gas."  Sometimes  called  "safety  oil."  Benzine,  or 
benzolene,  boils  from  148°  to  160°,  used  as  a  solvent  in  making  paints  and 
varnishes.  The  most  important  product  of  petroleum  is  that  portion  which 
distils  between  176°  and  218°,  and  which  constitutes  kerosene  and  other  oils 
used  for  burning  in  lamps.  An  oil  to  be  safely  used  for  burning  in  lamps 
should  not  "flash,"  or  give  off  inflammable  vapor,  below  37.4°,  and  should  not 
burn  at  temperatures  below  149°.  The  better  grades  of  kerosene  have  a  flash 
point  of  from  45°  to  65°. 

From  the  residue  remaining  after  the  separation  of  the  kerosene,  many 
other  products  are  obtained.  Lubricating  oils,  of  too  high  boiling-point  for 
use  in  lamps.  Paraffin,  a  white,  crystalline  solid,  fusible  at  45°-65°,  which 
is  used  in  the  arts  for  a  variety  of  purposes  formerly  served  by  wax,  such  as 
the  manufacture  of  candles.  In  the  laboratory  it  is  very  useful  for  coating  the 
glass  stoppers  of  bottles,  and  for  other  purposes,  as  it  is  not  affected  by  acids 
or  by  alkalies.  It  is  odorless,  tasteless,  insoluble  in  H2O  and  in  cold  alcohol; 
soluble  in  boiling  alcohol  and  in  ether,  fatty  and  volatile  oils  and  mineral  oils. 
It  is  also  obtained  by  the  distillation  of  certain  varieties  of  coal,  and  is  found 
in  nature  in  fossil  wax  or  ozocerite. 

The  products  known  as  vaseline,  cosmoline,  etc.,  are  mixtures  of  para- 
ffin and  the  heavier  petroleum  oils.  Their  consistency  depends  upon  the  relative 
proportion  of  the  higher  paraffins,  of  increasing  fusing-point,  which  they  con- 
tain, from  the  oily  petrolatum  liquidum  (U.  S.  P.),  to  the  hard  petrolatum  or 
petrolatum  album  (U.  S.  P.).  Like  petroleum  itself,  its  various  commercial 
products  are  not  definite  compounds,  but  mixtures  of  the  hydrocarbons  of  this 
series. 

HALOID  DERIVATIVES  OF  THE  PARAFFINS. 

By  the  action  of  Cl  or  Br,  upon  the  paraffins,  or  by  the  action  of 
HC1,  HBr  or  HI  upon  the  corresponding  hydroxides,  the  monohydric 


HALOID   DERIVATIVES   OF   THE   PARAFFINS  205 

alcohols/ compounds  are  obtained  in  which  one  of  the  H  atoms  of  the 
hydrocarbon  has  been  replaced  by  an  atom  of  Cl,  Br  or  I: 

C2H6+Br2=:C2H5Br+HBr,  or 

C2H5OH+HC1=C2H5C1+H20 

Or  they  are  more  readily  obtained  by  the  action  of  the  phosphorus 
halides,  or  of  the  halogen  in  presence  of  phosphorus  upon  the  mono- 
hydric  alcohols: 

CH3.CH2OH+PC15=CH3.CH2C1+POC13+HC1 

These  monohalogen  paraffins,  or  haloid  ethers,  or  haloid  esters, 
or  alkyl  halides,  may  also  be  considered  as  the  chlorides,  etc.,  of  the 
alcoholic  radicals,  methyl,  etc. 

When  Cl  is  allowed  to  act  upon  CH4,  it  replaces  a  further  number 
of  H  atoms  until  finally  carbon  tetrachloride,  CC14,  is  produced. 
Considering  marsh  gas  as  methyl  hydride,  CH3.H,  the  first  product 
of  substitution  is  methyl  chloride,  CH3C1;  the  second  monochlor- 
methyl  chloride,  CH2C1.C1;  the  third  dichlormethyl  chloride,  or 
chloroform,  CHC12.C1 ;  and  the  fourth  carbon  tetrachloride,  CC14. 

Similar  derivatives  are  formed  with  Br  and  I,  and  with  the  other 
hydrocarbons  of  the  series. 

Nascent  hydrogen  reduces  all  of  the  halogen  derivatives  to  the 
parent  hydrocarbons: 

CHC13+3H2=CH4+3HC1 

These  compounds  are  of  great  service  for  the  introduction  of  their 
alkyls  into  other  molecules.  Thus,  benzene  and  methyl  chloride  form 
methyl  benzene: 

C6H6+CH3C1=CCH5.CH3+HC1 

Caustic  potash  or  soda  in  alcoholic  solution  splits  off  the  halogen 
and  water,  with  formation  of  an  unsaturated  hydrocarbon: 
CH3.CHJBr+KOH=CH2  :CH2+KBr+H20 

Heated  with  aqueous  potash  the  haloid  esters  produce  the  cor- 
responding alcohols: 

CH3.CH2Br+KOH=CH3.CH2OH+KBr 

Heated  with  alcoholic  solution  of  potassium  cyanide  at  100°,  the 
haloid  esters  produce  the  alkyl  cyanides: 

CH3.CH2I+KCN=CH3.CH2.CN+KI 
They  also  combine  with  ammonia  to  form  amines : 
CH3C1+NH3=CH3.NH2+HC1 

Methyl  Chloride — CH3C1 — 50.5 — is  a  colorless  gas,  slightly  solu- 
ble in  H20,  and  having  a  sweetish  taste  and  odor.  It  is  prepared 
commercially  by  heating  trimethylammonium  chloride  (obtained  by 
distilling  beet  sugar  molasses)  : 

3N(CH3)3HC1=2CH3C1+2N(CH3)3+NH2CH3+HC1 


206  TEXT-BOOK    OF    CHEMISTRY 

It  may  be  condensed  to  a  liquid  which  boils  at  — 22°,  in  which 
form  it  is  used  in  ice  machines,  as  a  spray  in  neuralgia,  and  as  an 
anesthetic;  for  the  latter  uses  either  alone  or  mixed  with  CHC13, 
C4H100,  or  C2H5C1.  It  burns  with  a  greenish  flame. 

Dichlormethane  —  Methene  chloride  —  Methylene  chloride  — 
Monochlormethyl  chloride — CH2C12 — 85 — is  obtained  by  the  action 
of  Cl  upon  CH4,  and  by  the  reduction  of  CHC13  by  nascent  hydrogen. 

It  is  a  colorless,  oily  liquid;  boils  at  40°;  sp.  gr.  1.36;  its  odor 
is  similar  to  that  of  chloroform ;  it  is  very  slightly  soluble  in  H.,0  and 
is  not  inflammable.  It  has  been  used  as  an  anesthetic,  but  has  been 
discarded  as  being  less  safe  than  chloroform. 

Trichlormethane — Methcnyl  chloride — Dichlormethyl  chloride — 
Chloroform— Chloroformum  (U.  S.  P.)— CHC13— 119.5. 

Chloroform  is  manufactured  by  the  action  of  bleaching  powder 
upon  acetone,  the  reaction  being  expressed  by  the  equation: 

2CO(CH3)2+6CaCl(OCl)=2CHCl3+2Ca(HO)2+ 
(CH3COO)2Ca+3CaCl2 

It  is  best  obtained  pure  by  heating  chloral  hydrate  with  an  alkali : 
C2HC13(OH)2+KOH=CHC13+HCOOK+H20 

It  is  a  colorless,  volatile  liquid,  having  a  strong,  agreeable,  ether- 
eal odor,  and  a  sweet  taste ;  sp.  gr.  1.497 ;  very  sparingly  soluble  in 
H20 ;  miscible  with  alcohol  and  ether  in  all  proportions ;  boils  at 
60.8°.  It  is  a  good  solvent  for  many  substances  insoluble  in  H20, 
such  as  phosphorus,  iodine,  fats,  resins,  caoutchouc,  gutta-percha 
and  the  alkaloids. 

It  ignites  with  difficulty,  but  burns  from  a  wick  with  a  smoky,  red 
flame,  bordered  with  green.  It  is  not  acted  on  by  H2S04,  except  after 
long  contact,  when  HC1  is  given  off.  In  direct  sunlight  Cl  converts 
it  into  CC14  and  HC1.  The  alkalies  in  aqueous  solution  do  not  act 
upon  it,  but  when  heated  with  them  in  alcoholic  solution,  it  is  decom- 
posed with  formation  of  chloride  and  formate  of  the  alkaline  metal: 

CHC13+4KOH=H.COOK+3KC1+2H20 

When  perfectly  pure  it  is  not  altered  by  exposure  to  light ;  but  if 
it  contains  compounds  of  N,  even  in  very  minute  quantity,  it  is 
gradually  decomposed  by  solar  action  into  HC1,  Cl  and  other  sub- 
stances. When  used  as  an  anesthetic  chloroform  should  not  be 
colored  by  agitation  with  concentrated,  colorless  sulphuric  acid,  and 
should  color  the  latter  only  faintly  yellow,  or  not  at  all;  and  when 
it  is  evaporated  the  remaining  film  of  moisture  should  have  no  taste 
or  odor  other  than  those  of  chloroform. 

Analytical  Characters. —  (1)  Add  a  little  alcoholic  solution  of 
potash  and  2-3  drops  of  aniline  and  warm:  the  disagreeable  odor  of 
isobenzonitrile  (q.v.)  is  produced.  (2)  Vapor  of  CHC13,  when  passed 
through  a  red-hot  tube,  is  decomposed  with  formation  of  HC1  and 


HALOID    DERIVATIVES    OF    THE    PARAFFINS  207 

Cl,  the  former  of  which  is  recognized  by  the  production  of  a  white 
ppt.,  soluble  in  ammonium  hydroxide,  in  an  acid  solution  of  silver 
nitrate.  This  test  does  not  afford  reliable  results  when  the  substance 
tested  contains  a  free  acid  and  chlorides.  (3)  Dissolve  about  0.01  gm. 
of  fi  naphthol  in  a  small  quantity  of  KOH  solution,  warm,  and  add 
the  suspected  liquid;  a  blue  color  is  produced.  (4)  Add  about  0.3 
grm.  resorcinol  in  solution,  and  3  gtts.  NaOH  solution  and  boil 
strongly;  in  the  presence  of  CHC13  a  red  color  is  produced.  But 
the  liquid  exhibits  no  fluorescence  (p.  232). 

Toxicology. — The  action  of  chloroform  varies  as  it  is  taken  by  the  stomach 
or  by  inhalation.  In  the  former  case,  owing  to  its  insolubility,  but  little  is 
absorbed,  and  the  principal  action  is  the  local  irritation  of  the  mucous  sur- 
faces. Recovery  has  followed  a  dose  of  four  ounces,  and  death  has  been  caused 
by  one  drachm,  taken  into  the  stomach.  Chloroform  vapor  acts  much  more 
energetically,  and  seems  to  owe  its  potency  for  evil  to  its  paralyzing  influence 
upon  the  respiratory  nerve  centers,  and  upon  the  cardiac  ganglia.  While 
persons  suffering  from  heart  disease  are  particularly  susceptible  to  tfye  para- 
lyzing effect  of  chloroform  vapor,  there  are  many  cases  recorded  of  death  from 
the  inhalation  of  small  quantities,  properly  diluted,  in  which  no  heart  lesion 
was  found  upon  a  post-mortem  examination.  Chloroform  is  apparently  not 
altered  in  the  system. 

No  chemical  antidote  for  chloroform  is  known.  When  it  has  been  swal- 
lowed, stomach-lavage  and  emetics  are  indicated;  when  taken  by  inhalation,  a 
free  circulation  of  air  should  be  established  about  the  face;  artificial  respira- 
tion and  the  application  of  the  induced  current  to  the  sides  of  the  neck  and 
epigastrium  should  be  resorted  to. 

Carbon  Tetrachloride — CC14 — 154 — is  formed  by  the  prolonged 
action,  in  sunlight,  of  Cl  upon  CH3C1  or  CHC13 ;  or  more  rapidly,  by 
passing  Cl,  charged  with  the  vapor  of  carbon  disulphide,  through  a 
red-hot  tube,  and  purifying  the  product. 

It  is  a  colorless,  oily  liquid,  insoluble  in  H20 ;  soluble  in  alcohol 
and  in  ether;  sp.  gr.  1.56;  boils  at  78°.  Its  vapor  is  decomposed  at  a 
red  heat  into  a  mixture  of  the  dichloride,  C2C14,  trichloride,  C2C16, 
and  free  Cl. 

Tribrommethane — DibromometJiyl  bromide — Methenyl  bromide — 
Bromoform — CHBr2.Br — 253 — is  prepared  by  gradually  adding  Br 
to  a  cold  solution  of  KOH  in  methyl  alcohol  until  the  liquid  begins 
to  be  colored;  and  rectifying  over  CaCl2. 

A  colorless,  aromatic,  sweet  liquid;  sp.  gr.  2.13;  boils  at  150°- 
152  °  ;  solidifies  at  — 9  °  ;  sparingly  soluble  in  H20  ;  soluble  in  alcohol 
and  ether.  Boiled  with  alcoholic  KOH  it  is  decomposed  in  the  same 
way  as  in  CHC13. 

Its  physiological  action  is  similar  to  that  of  CHC13.  It  occurs  as 
an  impurity  of  commercial  Br,  accompanied  by  carbon  tetrabromide, 
CBr4. 

Triiodomethane — Diiodomethyl  iodide— MetJienyl  iodide — lodo- 
form— lodoformum,  (U.  S.  P.)— CHLI— 394.— Formed  like  CHC13, 


208  TEXT-BOOK   OF   CHEMISTRY 

and  CHBr3,  by  the  combined  action  of  KOH  and  the  halogen  upon 
alcohol ;  it  is  also  produced  by  the  action  of  I  upon  a  great  number  of 
organic  substances,  and  is  usually  prepared  by  heating  a  mixture  of 
alkaline  carbonate,  H20,  I  and  ethylic  alcohol,  and  purifying  the  prod- 
uct by  recrystallization  from  alcohol.  It  is  also  produced  from  acetone 
by  making  a  solution  containing  50  gm.  KI,  6  gm.  acetone,  and  2  gm. 
NaOH  in  2  L.  H20  and  gradually  adding  a  dilute  solution  of  KC1O3. 
Triiodoaldehyde  and  triiodoacetone  are  formed  as  intermediate 
products. 

lodoform  is  a  solid,  crystallizing  in  yellow,  hexagonal  plates, 
which  melt  at  120  °.  It  may  be  sublimed,  a  portion  being  decomposed. 
It  is  insoluble  in  water,  acids  and  alkaline  solutions;  soluble  in  alco- 
hol, ether,  carbon  disulphide,  and  the  fatty  and  essential  oils;  the 
solutions,  when  exposed  to  the  light,  undergo  decomposition  and 
assume  a  violet-red  color.  It  has  a  sweet  taste,  and  a  peculiar,  pene- 
trating odor,  resembling,  when  the  vapor  is  largely  diluted  with 
air,  that  of  saffron.  When  heated  with  potash  a  portion  is  decom- 
posed into  formate  and  iodide,  while  another  portion  is  carried  off 
unaltered  with  the  aqueous  vapor.  It  contains  96.7%  of  its  weight 
of  iodine. 

Ethyl  Chloride — Hydrochloric  or  muriatic  ether — C2H5C1 — 64.5. 
— A  colorless,  ethereal  liquid;  boils  at  11°;  obtained  by  passing 
gaseous  HC1  through  ethylic  alcohol  to  saturation,  and  distilling 
over  the  water-bath: 

C2H5OH+HC1=H20+C2H5C1 

It  is  now  used  to  produce  cold  by  spraying.  The  liquid  and 
vapor  are  readily  inflammable. 

Ethyl  Bromide  Hydrobromic  ether — C2H3Br — 109 — A  colorless,  ethereal 
liquid;  boils  at  40.7°,  obtained  by  the  combined  action  of  P  and  Br  on  ethylic 
alcohol.  It  has  been  used  as  an  anesthetic  in  minor  surgery. 

Ethyl  Iodide — Hydriodic  ether — CjH5I — 156 — is  prepared  by  placing  abso- 
lute alcohol  and  P  in  a  vessel  surrounded  by  a  freezing  mixture  and  gradually 
adding  I.  When  the  action  has  ceased,  the  liquid  is  decanted,  distilled  over  the 
water-bath  and  the  distillate  washed  and  rectified.  It  is  a  colorless  liquid; 
boils  at  72.2°;  has  a  powerful,  ethereal  odor;  burns  with  difficulty.  It  is 
largely  used  in  the  aniline  industry. 

OXIDATION  PRODUCTS  OF  THE  PARAFFINS. 

Many  important  and  varied  classes  of  compounds  are  derivable  from  the 
paraffins  by  oxidation: 

One  of  these  may  be  considered  as  derived  *  from  the  hydrocarbon  by  the 
introduction  of  an  oxygen  atom  between  two  of  its  hydrocarbon  groups.  Thus 
from  the  hydrocarbon  butane,  CH3.CHj.CH2.CH3  we  may  derive  the  oxides  CH,. 

*  Note:  The  words  "derived"  and  "  obtained"  are  not  used  synonymously.  One  substance  is 
said  to  he  derived  from  another  when  there  is  such  relation  between  their  molecular  structures 
that  tin'  constitutional  formula  of  the  more  complex  may  l*>  produced  from  that  of  the  more  simple  by 
substitution.  A  method  of  obteution  is  a  process  by  which  a  substance  is  manufactured,  and 
does  not  imply  any  relation  between  the  molecular  structures  of  the  product  and  parent,  al- 
though such  may,  and  very  frequently  does,  exist. 


OXIDATION   PRODUCTS   OF   THE   PARAFFINS 


209 


CH2.O.CH2CH3  and  CH3.O.CH2.CH2.CH3.  These  are  the  true  oxides  of  the  alkyls, 
and  are  known  as  simple  and  mixed  ethers,  according  as  the  oxygen  atom  is 
symmetrically  or  unsymmetrically  introduced  or  two  oxygen  atoms  may  be 
thus  introduced;  as  in  the  formals  (p.  232)  :  CH3O.CH,O.CH3.  Or,  in  other 
classes  of  compounds,  an  oxygen  atom  may  be  interpolated  as  in  the  ethers,  and 
one  or  more  of  the  hydrocarbon  groups  may  be  also  oxidized.  In  this  manner 
compounds  of  very  diverse  nature  are  derived:  Esters,  such  as  ethyl  acetate, 
CH3.CO.O.CH2.CH3;  acid  anhydrides,  or  acidyl  oxides,  such  as  acetic  anhy- 
dride, CH3.CO.O.CO.CH3;  certain  acids,  such  as  diglycollic  acid,  COOH.CH2.- 
O.CH2.COOH,  and  certain  dihydric  alcohols,  such  as  diethylene  glycol, 
CH2OH.CH2.O.CH2.CH2OH.  It  will  be  more  convenient  to  consider  "these  several 
classes  of  compounds  after  having  discussed  the  other  oxidation  products. 

Four  other  classes  are  more  closely  related  to  each  other.  They  may  be 
considered  as  being  derived  from  the  hydrocarbons  in  one  of  two  ways;  either 

( 1 )  By  the  interpolation  or  substitution,  or  both,  of  an  oxygen  atom  or 
atoms  in  one  of  the  groups  CH3,  CH2,  or  CH  of  the  parent  hydrocarbon  (see 
formulae  on  p.  210).  Thus: 

(H2:C.H)'    becomes    (H2:CO.OH)';     (0:C.H)'    or    (O:C.O.H)' 
(H.C.H)"  "  (H.C.O.H)"  or     (C:0)"  and 

(C.H)'"  (C.O.H)'" 

and  by  the  oxidation  of  a  single  group  in  the  hydrocarbon:  isopentane; 
(CH3)2:CH.CH2CH3  the  following  products  may  be  obtained: 

(CH3)2         (CH3)2         (CH3)2         (CH3)2         (CH3)2         (CH3)2 


CH 

CH 

CH 

CH 

CH 

C.O.H 

CH2 

CH2 

CH2 

H.C.O.H 

C:0 

CH2 

I 

1 

| 

1 

1 

1 

H2jC.O.H 

O:C.H 

0:C.O.H 

CH3 

CH3 

CH3 

Primary 
Alcohol. 

Aldehyde. 

Acid. 

Secondary 
Alcohol 

Ketone. 

Tertiary 
Alcohol. 

Isobutyl 

Valeral- 

Isovaler- 

Methyl 

Methyl 

Dimethyl 

Carbinol. 

dehyde. 

ianic    Acid. 

isopropyl 

isopropyl 

ethyl 

Carbinol. 

Ketone. 

Carbinol. 

(2)  Or  these  compounds  may  be  considered  as  produced  by  the  substitu- 
tion of  hydroxyls  (  OH  )  ,  for  one  or  more  of  the  hydrogen  atoms  of  the  hydro- 
carbon, it  being  remembered  that  when  a  substance  is  thus  produced  in  which 
two  hydroxyls  are  attached  to  the  same  carbon  atom,  water  separates,  except 
under  the  circumstances  referred  to  on  page  197.  Thus  from  the  hydrocarbon: 
propane,  CH3.CH2.CH3,  the  following  products  may  be  derived  by  substitution 
in  a  single  hydrocarbon  group: 


CH3.CH2.C      Q|j=:Primary  alcohol; 

CH3.CH2.C  /EQH  }  2-H20=CH3.CH2.C  /**  ^Aldehyde  ; 

CH3.CH2.C;  (OH)3—  H20=CH3.CH2.C  ^H=Acid; 

CH3.  (  CH.OH  )  .CH3=Secondary  alcohol  ; 

CH3.  (  C  :  [OH]  2  )  .CH3—  H20=CH3.  (  C  :  0  )  .CH3=Ketone. 


When  the  number  of  hydroxyls  substituted  in  each  hydrocarbon  group  ex- 
ceeds one,  the  number  of  derivatives  increases  rapidly  with  an  increasing  num- 


210  TEXT-BOOK    OP    CHEMISTRY 

her  of  C  atoms  in  the  parent  hydrocarbon.     Thus  the  second  term  of  the  series, 
CII3.CH3,  yields   nine  derivatives: 

I.  II.  III. 

CHaOH  CH(OH)2  0:C.H  C(OH)3  O:C.OH 

I    '  —  H20=        |  |  —  H,0=        | 

CH3  CH3  CH3  CH3  CH3 

Kt  hylic  Acetic  Acetic 

Alcohol.  Aldehyde.  Acid. 

IV.  V.  VI. 

CH3OH               CH(OH)2               0:C.H  CH(OH)2             O:C.H 

I             -H20=         |  —  2H20=        | 

CH2OH               CH2OH                  H2:C.OH  CH(OH),            O:C.H 

Klhylene                                                         (Myrolyl  Glyoxal. 
Olycol.                                                       Aldehyde. 

VII.  VIII.  IX. 

C(OH)S  0:C.OH 

C(OH)3  0:C.OH  C(OH)3  0:C.OH 


—  H20=       I  /r/nTTt  Trr/OH  —  2H20= 

CH2OH  H2:C.OH  "\OH        C(OH)3  O:C.OH 


Glycollic  Glyoxylic  Oxalic 

Acid.  Acid.  Acid. 

There  are  twenty-nine  possible  derivatives  of  the  third  hydrocarbon, 
CH3.CH2.CH3. 

The  four  classes  of  oxidation  products  under  consideration  are: 

A.  The  alcohols,  subdivided  into    (a)   Primary,  containing  the 
group—  C^QJJ;   (b)  Secondary,  containing  the  group  ^C/QJJ;  and 
(c)  Tertiary,  containing  the  group  EE  C.OH  ; 

B.  The  aldehydes,  containing  the  group  —  C^QH  ; 

C.  The  ketones,  containing  the  group=C=0  ;  and 

//  ^\ 

D.  The  carboxylic  acids,  containing  the  group  carboxyl :  — C 

ALCOHOLS— HYDROCARBON  HYDROXIDES. 

These  substances  are  mainly  characterized  by  their  power  of 
entering  into  double  decomposition  with  acids  to  form  neutral  com- 
pounds, called  esters,  water  being  at  the  same  time  formed  at  the 
expense  of  both  alcohol  and  acid.  They  are  the  hydroxides  of  hy- 
drocarbon radicals,  the  alkyls,  and  as  such  resemble  the  metallic 
hydroxides,  while  the  esters  are  the  counterparts  of  the  metallic 
salts : 

(C2H5)   )  Q        (C2H30)    )  0_  (C2H30)   )  Q       II  j I  Q 
HfC  H     f  C  (C2H5)  \  C    'HP 

Ethyl   hydroxide.  Act-tic    acid         Ethyl  acetate.        Water. 

o  + 

Potassium  Acetic    acid  Potassium  Water, 

hydroxide.  acetate. 


ALCOHOLS  211 

Or  they  may  be  regarded  as  substances  derived  from  the  hydro- 
carbons by  the  substitution  of  one  or  more  hydroxyls  for  one  or  more 
hydrogen  atoms.  Alcohols  containing  one  OH  are  designated  as 
monoatomic  or  monohydric ;  those  containing  two  OH  groups  are 
diatomic  or  dihydric,  etc. : 


CH2OH 

CH2OH 

CH2OH 

CH2OH 

CH2OH 

CH2OH 

CH2 

CH2 

CHOH 

(CHOH)2 

.  (CHOH)3 

(CHOH)4 

k 

CH2OH 

CH2OH 

CH2OH 

CH2OH 

CH2OH 

Propvlic 

Propyl 

Glycerol, 

Erythrol, 

Arabite, 

Mannitol, 

Alcohol, 

Glycol, 

Triatomic. 

Tetratomic. 

Pentatomic. 

Hexatomic. 

Monoatomic. 

Diatomic, 

MONOATOMIC,  OR  MONOHYDRIC  ALCOHOLS. 

Beginning  with  the  third  member  of  the  series,  an  increasing 
number  of  isomeres  of  the  higher  terms  are  known. 

I.  Some  of  these  alcohols  yield  on  oxidation,  first,  an  aldehyde 
containing  the  group  (CHO)'  and  then  an  acid  containing  the  group 
(COOH)',  both  aldehyde  and  acid  containing  the  same  number  of 
carbon  atoms  as  the  alcohol.     These  alcohols  contain  the  character- 
izing group  (CH2OH)',  and  are  called  primary  alcohols,  e.g.,  ethylic 
alcohol:  CH3.CH2OH. 

II.  Other  monoatomic  alcohols  yield  on  oxidation  not  an  aldehyde 
or  an  acid,  but  a  ketone,  containing  the  group  (CO)"  and  the  same 
number  of  carbon  atoms  as  the  alcohol.     These  alcohols  contain  the 
characterizing  group  (CHOH)",  and  are  called  secondary  alcohols, 
or  4soalcohols,  e.g.,  Isopropyl  alcohol :  CH3.CHOH.CH3. 

III.  Still  other  alcohols  yield  on  oxidation  either  two  or  more 
acids,  or  an  acid  and  a  ketone,  whose  molecules  contain  a  less  number 
of  carbon  atoms  than  the  alcohol  from  which  they  were   derived. 
These  alcohols  contain  the  characterizing  group    (COH)'",  and  are 
called  tertiary  alcohols,  e.g.,  Tertiary  butyl  alcohol,    (CH3)3:COH. 

The  monohydric  alcohols  are  also  the  hydroxides  of  *Jie  alkyls 
(p.  202). 

Nomenclature. — Names  of  alcohols  terminate  in  ol;  and  the  termination  ol 
is  reserved  for  the  names  of  alcohols  and  of  phenols.  The  "  Geneva  "  names  of 
the  monohydric  alcohols  are  derived  from  tho^e  01  the  corresponding  hydrocar- 
bons by  the  substitution  of  the  syllable  ol  for  the  terminal  e:  Thus  H.CH2OH 
is  methanol;  CH3.CH2OH  etlnnol;  CH3.CH2CH2OH,  1-propanol;  CH3.CHOH.CH3, 
2-propanol,  etc. 

Kolbe's  system  of  naming  the  monoatomic  alcohols  is  more  generally  fol- 
lowed. It  refers  the  names  of  the  higher  alcohols  back  to  that  of  the  first, 
H.CH2OH,  which  is  called  carl'nol;  the  names  of  the  radicals  contained  in  the 
superior  homologues  being  preL'ed  to  the  word  "carbinol"  in  the  construction 
of  their  names.  Thus  the  grapf  'c  formulae  and  carbinol  names  of  the  eight 
possible  amylic  alcohols  are  as  i  Mows: 


212  TEXT-BOOK   OF   CHEMISTRY 

Primary.  Secondary. 

(1)   CH3.CH2.CH2.CH2.CH2OH  ,.,   CH: 

\    '   ( *i i 

Butyl  Carbinol.  U±l: 

(Normal   ainyllc    alcohol.)  Diethyl    t'arbinol. 


(2)   ~gs^  CH.CH2.CH2OH  (fi) 

Isobutyl  Carbinol. 

(Amylic    alcohol    of  Methyl  n-propyl  Carbinol. 

fermentation.) 

<3>  CH,£H>H-CH°OH  (7)CT;>CH°/ 

Secondary    butyl    Carbinol.  Methyl    Isopropyl    Carbinol. 

(Active   amyiic  alcohol).  Tertiary. 
CH3\  CH3\ 

(4)   CH3— C.CH2OH  (8)  CH3— C.OH 

CH3/  CH3.CH2/ 

Tertiary  butyl  Carbinol.  Dimethyl  ethyl  Carbinol. 

Of  the  above,  numbers  1,  5  and  6  are  derived  from  the  normal  paraffin 
(1,  p.  202);  numbers  2,  3,  7  and  8  from  the  isoparaffin  (2),  and  number 
4  from  the  mesoparaffin  (3). 

.    General  Methods  of  Formation. —  (1)   By  the  action  of  freshly 
precipitated,  moist  silver  hydroxide  upon  the  haloid  esters: 

C2H5I+AgOH=C2H5OH+AgI 

(2)  By  the  saponification  of  their  esters  by  caustic  potash: 

C2H802.C2HB+KOH=C2H5.OH+C2H802K 

(3)  Primary  alcohols  are  produced  by  the  reduction  of  aldehydes, 
acid  chlorides,  or  anhydrides : 

C2H5.CHO+H2=C2H5.CH2OH,  or 

C2H5.COC1+2H2=C2H5.CH,OH+HC1,  or 

(CH3CO)20+2H2=CH3.CH2OH+CH3.COOH 

(4)  By  the  action  of  nitrous  acid  upon  the  primary  amines: 

CH3.CH2.NH2+HN02=CH3.CH2OH+N2+H20 

(5)  By  the  action  of  trioxymethylene  upon  the  alkyl  magnesium 
halides  (p.  291)  ;  the  alcohol  next  above  the  alkyl  contained  in  the 
organo-metallic  compound  being  formed.     This  reaction,   after  the 
trioxymethylene  splits  to  formic  aldehyde   (p.  228),  takes  place  in 
two  stages.    A  condensation  product  is  first  formed: 

CH3.CH2.Mg.Br.+H.CHO=CH3.CH2.CH2.O.Mg.Br. 
And  this  is  then  hydrolyzed : 
CH3.CH2.CH2.O.Mg.Br.+H20=CH3.CH2.CH2OH.+HO.Mg.Br. 

(p.  291). 

(6)  Secondary  alcohols  are  formed  by  the  reduction  of  ketones: 

CH3.CO.CH3+H2=CH3.CHOH.CH3. 

(7)  With   aldehydes   higher    than    formic    aldehyde,    alkyl   mag- 


ALCOHOLS  213 

nesium  halides  produce  secondary  alcohols,  the  reactions  occurring 
in  two  phases  as  in  (5)  : 

CH3.Mg.I.+CH3.CHO.=CH3.CH(CH3)O.Mg.I.  and 
CH3.CH(CH3).O.Mg.I.+H20=CH3.CHOH.CH3+HO.Mg.I. 

(8)  Tertiary  alcohols  are  produced  by  the  action  of  moist  silver 
hydroxide  upon  tertiary  alkyl  iodides.     Thus  tertiary  butyl  iodide 
yields  tertiary  butyl  alcohol: 

g£>  CI.CH.+ AgOH=  g£>  C  ( OH)  -CH3+AgI 

(9)  With  ketones  the  alkyl  magnesium  halides  produce  tertiary 
alcohol  by  reactions  similar  to  those  given  (in  5  and  7)  : 

CH3.Mg.Br+CH3.CO.CH3=:(CH3)2=(CH3).O.Mg.Br.    and 
(CH3)2:C(CH3).O.Mg.Br.+H20=(CH3)3  =  COH+HO.Mg.Br. 

(10)  Acetyl  chloride  or  anhydride   reacts  violently  with  alkyl 
magnesium  halides.     At  suitable  temperature  this  reaction  occurs  in 
two  stages: 

CH3.CO.Cl+CH3.MgCl=(CH3)2:CC1.0.MgCl.  and 
(CH3)2:CC1.0.Mg.Cl+CH3.MgCl=(CH3)3iCO.MgCl+MgCl2 

The  product  when  hydrolyzed  yields  a  tertiary  alcohol: 
(CH3)3.:CO.MgCl+H20=(CH3)3!COH+HO.MgCl.     (See  p.  389.) 

(11)  Tertiary  alcohols  are  also  produced  by  interaction  of  alkyl 
magnesium  halides  with  esters  of  monobasic  acids  (except  formic),  or 
with    carbonyl    chloride.      Formic    esters    yield    secondary    alcohols 
(p.  290). 

General    Reactions. —  (1)    The    monohydric    alcohols   react   with 
metallic  Na  or  K  to  form  double  oxides,  called  alcoholates : 

2CH3.CH2OH+Na2=H2+2CH3.CH2.O.Na. 

(2)  When  heated  with  acids  they  form  esters: 

CH3.CH.,OH+H2S04=CH3.CH2.HS04+H20,  or 
2CH3.CH2OH+H2S04==  ( CH3.CH2)  2S04+2H20 

(3)  When  heated  with  hydracids  they  form  alkyl  halides: 

CHS.CH2OH+HC1=CH3.CH2C1+H20 ; 

which,  in  turn,  when  reduced  by  nascent  hydrogen,  regenerate  the 
parent  hydrocarbon: 

CH3CH2C1+H2=CH3.CH3+HC1 

(4)  Their   products   of    oxidation   vary   according   as   they   are 
primary,  secondary  or  tertiary  (see  above)  : 

Primary: 

2CH8.GH2OH+02==2CH8.CfiO-f2H2O,  and 
CHS.CH3OH+02=CH3.COOH+H20 


214  TEXT-BOOK   OF   CHEMISTRY 

Secondary: 

2CH3.CHOH.CH3+02=2CH3.CO.CH3+2H20 
Tertiary : 

2 ( CH3) 3.COH+302=2CH3.CO.CH3+2H.COOH+2H20,  then 

CH3.CO.CH3+202=CH3.COOH+C02+H20,  and 

2H.COOH+02=2C02+2H20. 

Methyl  Hydroxide — Carbinol — Pyroxylic  spirit — Methylic  alco- 
hol—Wood alcohol— Wood  spirit— H.CH2OH=32— may  be  formed 
from  marsh-gas,  CH3H,  by  first  converting  it  into  the  iodide,  and 
acting  upon  this  with  potassium  hydroxide : 

CH3I+KOH=KI+H.CH2OH 

It  is  usually  obtained  by  the  destructive  distillation  of  wood. 
The  pure  hydroxide  can  only  be  obtained  by  decomposing  a  crystal- 
line compound,  such  as  methyl  oxalate,  and  rectifying  the  product 
until  the  boiling-point  is  constant  at  66.5°. 

Pure  methyl  alcohol  is  a  colorless  liquid,  having  an  ethereal  and 
alcoholic  odor,  and  a  sharp,  burning  taste;  sp.  gr.  0.814  at  0°;  boils 
at  66.5°;  burns  with  a  pale  flame,  giving  less  heat  than  that  of 
ethylic  alcohol;  mixes  with  water,  alcohol,  and  ether  in  all  pro- 
portions; is  a  good  solvent  of  resinous  substances,  and  also  dissolves 
sulphur,  phosphorus,  potash,  and  soda. 

Methyl  hydroxide  is  not  affected  by  exposure  to  air  under  ordinary 
circumstances,  but  in  the  presence  of  platinum-black  it  is  oxidized, 
with  formation  of  the  corresponding  aldehyde,  formaldehyde,  and 
acid,  formic  acid.  Hot  HN03  decomposes  it  with  formation  of 
nitrous  fumes,  formic  acid  and  methyl  nitrate.  It  is  acted  upon  by 
H2S04  in  the  same  way  as  ethyl  alcohol.  The  organic  acids  form 
methyl  esters  with  it. 

Methylated  spirit  is  ethyl  alcohol  containing  one-ninth  its  vol- 
ume of  wood  spirit. 

Ethyl  Hydroxide — Ethylic  alcohol — Methyl  carbinol — Vinic 
alcohol— Alcohol— Spirits  of  wine— CH3.CH2OH— 46. 

Preparation. — Industrially  alcohol  and  alcoholic  liquids  are  ob- 
tained from  substances  rich  in  starch  or  glucose. 

The  manufacture  of  alcohol  consists  of  three  distinct  processes: 
(1)  the  conversion  of  starch  into  sugar;  (2)  the  fermentation  of  the 
saccharine  liquid;  (3)  the  separation,  by  distillation,  of  the  alcohol 
formed  by  fermentation. 

( 1 )  The  raw  materials  for  the  first  process  are  malt  and  some  sub- 
stance (grain,  potatoes,  rice,  corn,  etc.)  containing  starch.  Malt  is 
barley  which  has  been  allowed  to  germinate,  and,  at  the  proper  stage 
of  germination,  roasted.  During  this  growth  there  is  developed  in 
the  barley  a  peculiar  nitrogenous  principle  called  diastase.  The 
starchy  material  is  mixed  with  a  suitable  quantity  of  malt  and  \vjiter. 


ALCOHOLS  215 

and  the  mass  maintained  at  a  temperature  of  65°-70°  for  two  to 
three  hours,  during  which  the  diastase  rapidly  converts  the  starch 
into  dextrin,  and  this  in  turn  into  maltose  and  glucose. 

(2)  The  saccharine  fluid,  or  wort,  obtained  in  the  first  process,  is 
drawn  off,  cooled,  and  yeast  is  added.  As  a  result  of  the  growth  of 
the  yeast-plant,  a  complicated  series  of  chemical  changes  takes  place, 
the  principal  one  of  which  is  the  splitting  up  of  the  glucose  into 
carbon  dioxide  and  alcohol: 


There  are  formed  at  the  same  time  small  quantities  of  glycerol, 
succinic  acid,  and  propylic,  butylic,  and  amylic  alcohols. 

(3)  An  aqueous  fluid  is  thus  obtained  which  contains  3-15  per 
cent,  of  alcohol.  This  is  then  separated  by  the  third  process,  that  of 
distillation  and  rectification.  The  apparatus  used  for  this  purpose 
has  been  so  far  perfected  that  by  a  single  distillation  an  alcohol  of 
90-95  per  cent,  can  be  obtained. 

In  some  cases  alcohol  is  prepared  from  fluids  rich  in  glucose,  such 
as  grape-juice,  molasses,  syrup,  etc.  In  such  cases  the  first  process 
becomes  unnecessary. 

Commercial  alcohol  always  contains  H20,  and  when  pure  or 
absolute  alcohol  is  required,  the  commercial  product  must  be  mixed 
with  some  hygroscopic  solid  substance,  such  as  quicklime,  from 
which  it  is  distilled  after  having  remained  in  contact  twenty-four 
hours. 

Fermentation.  —  This  term  (derived  from  fervere^to  boil)  was 
originally  applied  to  alcoholic  fermentation,  by  reason  of  the  bub- 
bling of  the  saccharine  liquid  caused  by  the  escape  of  C02  ;  subse- 
quently it  came  to  be  applied  to  all  decompositions  similarly  attended 
by  the  escape  of  gas. 

At  present  it  is  used  by  many  authors  to  apply  to  a  number  of 
heterogeneous  processes;  and  some  writers  distinguish  between 
"true"  and  "false"  fermentation.  It  is  best  to  limit  the  appli- 
cation of  the  term  to  those  decompositions  designated  as  true  fer- 
mentations. 

Fermentation  is  a  decomposition  of  an  organic  substance,  pro- 
duced by  the  processes  of  nutrition  of  a  low  form  of  animal  or 
vegetable  life. 

The  true  ferments  are  therefore  all  organized  beings,  such  as 
torula  cerevisice,  producing  alcoholic  fermentation;  penicillium  glau- 
cum,  producing  lactic  acid  fermentation;  and  mycoderma  aceti,  pro- 
ducing acetic  acid  fermentation. 

Acetic  acid  fermentation.  The  micro-organism,  which  is  present 
in  the  air,  causes  the  alcohol  to  take  up  oxygen  from  the  air;  acetic 
acid  is  produced  : 

C2H5OH+02=:CH3.COOH+H20 


216  TEXT-BOOK    OF    CHEMISTRY 

Lactic  acid  fermentation.  The  micro-organism,  which  is  present 
in  the  air,  gets  into  the  milk  and  converts  the  lactose  into  lactic  acid : 

C12H22011+H20=4C3H603 

Butyric  acid  fermentation.  This  is  brought  about  when  decaying 
cheese  and  sour  milk  arc  brought  together;  the  lactic  acid  is  con- 
verted into  butyric  acid  by  the  butyric  ferment  which  is  present  in 
the  cheese: 

2C3H603=C3H7.COOH+2C02+2H2 

The  false  fermentations  are  not  produced  by  an  organized  body, 
but  by  a  soluble,  unorganized,  nitrogenous  substance,  whose  method 
of  action  is  as  yet  imperfectly  understood.  The  unorganized  fer- 
ments, such  as  diastase,  pepsin,  etc.,  are  called  enzymes. 

An  interesting  total  synthesis  of  alcohol  is  from  calcium  carbide, 
water  and  hydrogen.  Acetylene  is  formed  by  the  action  of  water 
upon  calcium  carbide: 

CaC2+2H20=CaH202+CJI2 

Vapors  of  acetylene  and  water,  heated  together  to  325°  unite  to 
form  aldehyde: 

C2H2+H20=CHO.CH3 

And  nascent  hydrogen  converts  aldehyde  into  alcohol : 
CHO.CH3+H2=CH2OH.CH3 

Properties. — Alcohol  is  a  thin,  colorless,  transparent  liquid,  hav- 
ing a  spirituous  odor  and  a  sharp,  burning  taste;  sp.  gr.  0.8095  at 
0°,  0.7939  at  15°;  it  boils  at  78.5°,  and  solidifies  at  —130.5°.  At 
temperatures  below  — 90°  it  is  viscous.  It  mixes  with  water  in  all 
proportions,  the  union  being  attended  by  elevation  in  temperature 
and  contraction  in  volume  (after  cooling  to  the  original  temperature). 
It  also  attracts  moisture  from  the  air  to  such  a  degree  that  abso- 
lute alcohol  only  remains  such  for  a  very  short  time  after  its  prepara- 
tion. It  is  to  this  power  of  attracting  H2O  that  alcohol  owes  its 
preservative  power  for  animal  substances.  It  is  a  very  useful  solvent, 
dissolving  a  number  of  gases,  many  mineral  and  organic  acids  and 
alkalies,  most  of  the  chlorides  and  carbonates,  some  of  the  nitrates, 
and  the  essences  and  resins.  The  sulphates  are  insoluble  in  alcohol. 
Alcoholic  solutions  of  fixed  medicinal  substances  arc  called  tinctures; 
those  of  volatile  principles,  spirits. 

The  action  of  oxygon  upon  alcohol  varies  according  to  the  con- 
ditions. I'mler  the  influence  of  energetic  oxidants.  such  as  chromic 
acid,  or,  when  alcohol  is  burned  in  the  air.  the  oxidation  is  rapid 
and  complete,  and  is  attended  by  the  extrication  of  much  heat,  and 
the  formation  of  carbon  dioxide  and  water: 

C2HeO+302=2C02+3H20 


ALCOHOLS  217 

Mixtures  of  air  and  vapor  of  alcohol  explode  upon  contact  with 
flame.  If  a  less  active  oxidant  be  used,  such  as  platinum-black,  or  by 
the  action  of  atmospheric  oxygen  at  low  temperatures,  a  simple 
oxidation  of  the  alcoholic  radical  takes  place,  with  formation  of  acetic 
acid  : 

CH3.CH2OH+O2=CH3.COOH+H20 

a  reaction  which  is  utilized  in  the  manufacture  of  acetic  acid 
and  vinegar.  If  the  oxidation  is  still  further  limited,  aldehyde  is 
formed : 

2CH3.CH2OH+02=2CH3.CHO+2H20 

If  vapor  of  alcohol  is  passed  through  a  tube  filled  with  platinum 
sponge  and  heated  to  redness,  or  if  a  coil  of  heated  platinum  wire  is 
introduced  into  an  atmosphere  of  alcohol  vapor,  the  products  of 
oxidation  are  quite  numerous :  among  them  are  water,  ethylene,  alde- 
hyde, acetylene,  carbon  monoxide,  and  acetal.  Heated  platinum  wire 
introduced  into  vapor  of  alcohol  continues  to  glow  by  the  heat  result- 
ing from  the  oxidation,  a  fact  which  has  been  utilized  in  the  thermo- 
cautery. 

Chlorine  and  bromine  act  energetically  upon  alcohol,  producing  a 
number  of  chlorinated  and  brominated  derivatives,  the  final  products 
being  chloral  and  bromal.  If  the  action  of  Cl  is  moderated,  alde- 
hyde and  HC1  are  first  produced.  Iodine  acts  quite  slowly  in  the 
cold  but  old  solutions  of  I  in  alcohol  (Tr.  iodine)  are  found  to  con- 
tain HI,  ethyl  iodide,  and  other  imperfectly  studied  products.  In 
the  presence  of  an  alkali,  I  acts  upon  alcohol  to  produce  iodoform, 
which  is  also  formed  under  like  conditions  from  aldehyde  or  acetone. 
Potassium  and  sodium  dissolve  in  alcohol  with  evolution  of  H;  upon 
cooling,  a  white  solid  crystallizes,  which  is  the  double  oxide  of  ethyl 
and  the  alkali  metal,  and  is  known  as  potassium  or  sodium  ethylate 
or  alcoholate.  Nitric  acid,  aided  by  a  gentle  heat,  acts  violently 
upon  alcohol,  producing  nitrous  ether,  brown  fumes,  and  products  of 
oxidation.  (For  the  action  of  other  acids  upon  alcohol  see  the  cor- 
responding esters  and  the  ethers.)  The  hydroxides  of  the  alkali 
metals  dissolve  in  alcohol,  but  react  upon  it  slowly;  the  solution  turns 
brown  and  contains  an  acetate.  If  alcohol  is  gently  heated  with 
HN03  and  nitrate  of  silver  or  of  mercury,  a  gray  precipitate  falls, 
which  is  silver  or  mercury  fulminate. 

Varieties. — It  occurs  in  different  degrees  of  concentration :  abso- 
lute alcohol  is  pure  alcohol,  C2H60.  It  is  not  purchasable,  and  must 
be  made  as  required.  Alcohol  dehydratum  (U.  S.  P.)  contains  not 
less  than  99  per  cent,  by  weight  of  C2H5OH.  The  so-called  absolute 
alcohol  of  the  shops  is  rarely  stronger  than  98  per  cent.  Alcohol 
(U.  S.  P.),  sp.  gr.  0.820,  contains  94  per  cent,  by  volume,  and 
spiritus  rectificatus,  sp.  gr.  0.838,  contains  84  per  cent.  This  is  the 
ordinary  rectified  spirit  used  in  the  arts.  Alcohol  dilutum  (U.  S.  P.) 


218  TEXT-BOOK   OF    CHEMISTRY 

used  in  the  preparation  of  tinctures,  contains  41  per  cent.  It  is  of 
about  the  same  strength  as  the  proof  spirit  of  commerce.  Denatured 
alcohol  is  alcohol  which,  while  fit  for  industrial  uses,  has  been  rendered 
unfit  for  drinking.  This  is  accomplished  by  the  addition  of  sub- 
stances, such  as  methyl  alcohol  and  pyridine  or  benzine. 

Analytical  Characters — (1)  Heated  with  a  small  quantity  of 
solution  of  potassium  dichromate  and  H2S04,  the  liquid  assumes  an 
emerald-green  color,  and,  if  the  quantity  of  C2H60  is  not  very 
small,  the  peculiar  fruity  odor  of  aldehyde  is  developed.  (2)  Warmed 
and  treated  with  a  few  drops  of  potash  solution  and  a  small  quantity 
of  iodine,  an  alcoholic  liquid  deposits  a  yellow,  crystalline  ppt.  of 
iodoform,  either  immediately  or  after  a  time.  (3)  If  HN03  is  added 
to  a  liquid  containing  C2H60,  nitrous  ether,  recognizable  by  its  odor, 
is  given  off.  If  a  solution  of  mercurous  nitrate  with  excess  of  HN03 
is  then  added,  and  the  mixture  heated,  a  further  evolution  of  nitrous 
ether  occurs,  and  a  yellow-gray  deposit  of  fulminating  mercury  is 
formed,  which  may  be  collected,  washed,  dried,  and  exploded.  (4) 
If  an  alcoholic  liquid  is  heated  for  a  few  moments  with  H2S04  diluted 
with  H20  and  distilled,  the  distillate,  on  treatment  with  H2S04  and 
potassium  permanganate,  and  afterward  with  sodium  thiosulphate, 
yields  aldehyde,  which  may  be  recognized  by  the  production  of  a  vio- 
let color  with  a  dilute  solution  of  fuchsin. 

None  of  the  above  reactions,  taken  singly,  is  characteristic  of 
alcohol. 

Alcohol  is  determined  quantitatively  in  simple  mixtures  of  alcohol 
and  water  by  determining  the  specific  gravity  and  referring  to  tables 
constructed  for  the  purpose.  In  alcoholic  beverages  100  cc.  of  the 
sample  is  distilled  until  75  cc.  have  passed  over ;  the  distillate  is  then 
made  up  to  100  cc.  with  water,  and  the  sp.  gr.  determined. 

Alcoholic  Beverages. — These  may  be  divided  into  four  classes: 

1. — Those  prepared  by  the  fermentation  of  malted  grain — beers,  ales  and 
porters. 

II. — Those  prepared  by  the  fermentation  of  grape  juice — wines. 

III. — Those  prepared  by  the  fermentation  of  the  juices  of  fruits  other  than 
the  grape — cider,  fruit-wines. 

IV. — Those  prepared  by  the  distillation  of  some  fermented  saccharine  liquid 
— ardent  spirits. 

Beer,  ale  and  porter  are  aqueous  infusions  or  decoctions  of  malted  grain, 
fermented  and  flavored  with  hops.  They  contain  all  of  the  soluble  constituents 
of  the  grain  and  hops,  plus  dextrins,  maltose,  glucose,  alcohol  and  carbon 
dioxide.  Their  alcoholic  contents  varies  from  1.5  to  9  per  cent,  absolute  alcohol 
by  weight.  They  contain  a  considerable  proportion  of  nitrogenous  material 
(0.4  to  1  per  cent.  N),  and  succinic,  lactic  and  acetic  acids.  The  most  serious 
adulterations  of  malt  liquors  consist  in  the  use  of  artificial  glucose  to  furnish 
a  part  of  the  alcohol,  and  in  the  use  of  strychnine,  picrotoxin,  picric  acid,  or 
other  bitter  principles  as  substitutes  for  hops. 

Wine  is  fermented  grape-juice.  The  expressed  juice,  called  the  must,  con- 
tains much  glucose,  the  fermentation  of  which  is  set  up  by  yeast-plants  growing 
upon  the  ^rape-skins.  In  red  \\ines  Hie  color  is  produced  by  solution  of  the 


ALCOHOLS  219 

coloring'  matter  of  the  skins  in  the  accumulating  alcohol.  The  same  agency 
causes  the  precipitation  of  a  part  of  the  hydropotassic  tartrate,  to  which  the 
grape  or  wine  owes  its  tartness.  Sweet  wines  are  made  from  grapes  rich  in 
glucose,  and  by  arresting  the  fermentation  before  the  sugar  has  been  com- 
pletely decomposed.  "Dry"  or  "brut"  wines,  which  are  not  sweet,  are  fermented 
to  completion.  "Light"  wines  are  such  as  contain  less  than  12  per  cent,  of 
alcohol,  although  they  sometimes  contain  as  much  as  16  per  cent.  They  are 
the  products  of  temperate  climates,  and  include  the  clarets,  Sauternes,  Bur- 
gundies, the  Rhine,  Moselle,  Australian,  Greek  and  Hungarian  wines,  and  the 
wines  of  the  northern  portions  of  Spain,  Italy  and  the  United  States.  The 
champagnes  also  belong  to  this  class,  and  are  sparkling  from  the  escape  of 
carbon  dioxide,  produced  by  a  secondary  fermentation  in  the  bottles,  and  held 
in  solution  by  its  own  pressure.  "Heavy"  wines  are  those  whose  alcoholic 
strength  is  greater  than  12  per  cent.,  usually  14  to  25  per  cent.  They  are  the 
products  of  warm  climates,  and  include  the  sherries  of  the  south  of  Spain,  the 
ports  of  Portugal,  the  Marsalas  of  the  south  of  Italy,  the  Madeiras,  and  the 
wines  of  southern  California.  The  adulteration  of  real  wine  is  practically 
limited  to  the  addition  of  coloring  matters,  and  to  "  fortification  "  by  the  addi- 
tion of  alcohol  or  brandy.  Liquids  are  also  manufactured  to  imitate  wines, 
which  contain  no  grape-juice. 

Cider  is  the  fermented  juice  of  the  apple,  and  contains  from  3.5  to  7.5  per 
cent,  of  alcohol. 

Spirits  are  prepared  by  fermentation  and  distillation.  They  differ  from 
beers  and  wines  in  containing  a  larger  percentage  of  alcohol,  35  to  50  per  cent., 
and  in  not  containing  any  of  the  non-volatile  constituents  of  the  grains  or 
fruits  from  which  they  are  prepared.  They  are  yellow  in  color  when  stored 
in  white  oak  casks  the  interior  of  which  has  been  burnt,  and  colorless  or  faintly 
yellow  when  kept  in  unburnt  casks.  Besides  alcohol  and  water  they  contain 
acetic,  butyric,  valeric  and  cenanthic  esters,  to  which  they  owe  their  flavor. 
They  include:  brandy,  sp.  gr.  0.929-0.934,  made  by  distilling  wine;  rum,  sp.  gr. 
0.914-0.926,  made  by  distilling  molasses;  and  whiskies  and  gins,  made  by  fer- 
menting and  distilling  grains,  wheat,  rye,  barley  or  maize.  The  peculiar  flavor 
of  Scotch  and  Irish  whiskies  is  derived  from  the  smoke  of  a  peat  fire;  that  of 
gin  is  produced  by  distilling  from  juniper  berries.  In  making  straight  whisky 
the  distillate  is  not  completely  defuselated  (p.  220),  and  by  slow  oxidation  the 
remaining  fusel  produces  the  esters  to  which  the  spirit  owes  its  flavor.  Hence 
when  newly  made  it  is  neither  palatable  nor  wholesome,  but  in  about  three 
years  in  wood  the  fusel  has  been  in  great  part  removed  by  oxidation,  the 
whisky  is  ripe,  and  continues  to  improve  with  age.  In  making  blend  whisky 
the  distillate  is  completely  defuselated  to  neutral  spirit,  and  the  product  is 
made  to  imitate  aged  whisky  more  or  less  closely  by  addition  of  esters,  "  bead- 
ing oil  "  and  other  chemicals. 

Liqueurs  or  cordials  are  spirits  sweetened  and  flavored  with  vegetable 
aromatics,  and  frequently  colored;  anisette  is  flavored  with  aniseed;  absinthe, 
with  wormwood ;curaQoa,  with  orange  peel;  kirschwasser,  with  cherries,  the 
stones  being  cracked  and  the  spirits  distilled  from  the  bruised  fermented  fruit; 
kiimmel,  with  cummin  and  caraway  seeds;  maraschino,  with  cherries;  noyau, 
with  peach  and  apricot  kernels. 

Propyl  Hydroxide — Ethyl  carbinol — Primary  propyl  alcohol — CH3.- 
CH2.CH2OH — 60 — is  produced,  along  with  ethylic  alcohol,  during  fermentation, 
and  obtained  by  fractional  distillation  of  marc  brandy,  from  cognac  oil,  huile 
de  marc  (not  to  be  confounded  with  oil  of  wine),  an  oily  matter,  possessing  the 
flavor  of  inferior  brandy,  which  separates  from  marc  brandy,  distilled  at  high 
temperatures;  and  from  the  residues  of  manufacture  of  alcohol  from  beet-root, 
grain,  molasses,  etc.  It  is  a  colorless  liquid,  has  a  hot  alcoholic  taste,  and  a 
fruity  odor;  boils  at  96.7°;  and  is  miscible  with  water.  It  has  not  been  put 


220  TEXT-BOOK   OP   CHEMISTRY 

to  any  use  in  the  arts.  Its  intoxicating  and  poisonous  actions  are  greater  than 
those  of  ethyl  alcohol.  It  exists  in  small  quantity  in  cider. 

Butyl  Alcohols — C4H9OH — 74. — The  four  butyl  alcohols  theoretically  pos- 
sible are  known  to  exist: 

Propyl  Carbinol — Primary  normal  butyl  alcohol — Hutyl  alcohol  of  fer- 
mentation— CH3.CH2.CH2.CH2OH — is  formed  in  small  quantities  during  alcoholic 
fermentation,  and  may  be  obtained  by  repeated  fractional  distillation  from  the 
oily  liquid  left  in  the  rectification  of  vinic  alcohol.  It  is  a  colorless  liquid; 
boils  at  116.8°.  It  is  more  actively  poisonous  than  ethyl  or  methyl  alcohol. 

C'TJ     V 

Isopropyl    Carbinol — Isobutyl    alcohol—  r,Tr3  /CH.CH2OH — occurs    in    the 

V^±13/ 

fusel  oil  obtained  in  the  products  of  fermentation  and  distillation  of  beet-root 
molasses.  It  is  a  colorless  liquid,  sp.  gr.  0.8032;  boils  at  108.4°. 

Ethyl-methyl    Carbinol — Secondary   butyl   alcohol— CH3— CH2\pTTOTT 

CH3/C 
a  liquid  which  boils  at  99°. 

CH3\ 
Trimethyl    Carbinol — Tertiary    butyl    alcohol,    CH3— COH — a  crystalline 

CH3/ 
solid  which  fuses  at  25°,  and  boils  at  82°. 

Amy  lie  Alcohols— C5Hn  OH— 88.— The  eight  amyl  alcohols  theo- 
retically possible  (see  p.  212)  are  known.  The  substance  usually 
known  as  amylic  alcohol,  potato  spirit,  fusel  oil,  is  the  primary 
alcohol,  ™3J>CH.CH2.CH2OH,  with  lesser  quantities  of  other  alco- 
hols, differing  in  nature  and  amount  with  the  grain  used,  and  the 
conditions  of  the  fermentation  and  distillation,  each  kind  of  "spirit" 
furnishing  and  containing  a  peculiar  fusel. 

In  the  process  of  manufacture  of  ardent  spirits  the  fusel  oil 
accumulates  in  great  part  in  the  still,  but  much  of  it  distils  over, 
and  is  more  or  less  completely  removed  from  the  product  by  the 
process  of  defuselation. 

The   individual   amylic   alcohols   have   the   following  characters: 

Butyl  carbinol;  normal  amylic  alcohol,— CH,.CH,.CHa.CH2.CH2OH— is  a 
colorless  liquid,  boils  at  137°.  Obtained  from  normal  butyl  alcohol,  or  from 
normal  amylamine.  It  yields  normal  valeric  acid  on  oxidation. 

Isobutyl    Carbinol— Amyl    alcohol— H5a^OH.CH2.OH,()H— is  the  princi- 

V^-LAg  / 

pal  constituent  of  the  fusel  oil  from  grain  and  potatoes.  It  i>  obtained  from 
the  last  milky  products  of  rectification  of  alcoholic  liquids.  These  are  shaken 
with  H20  to  remove  ethyl  alcohol,  the  supernatant  oily  fluid  is  decanted,  dried 
by  contact  with  fused  calcium  chloride,  and  distilled;  that  portion  which  passes 
over  between  128°  and  132°  being  collected. 

It  is  a  colorless,  oily  liquid,  has  an  acrid  taste  and  a  peculiar  odor,  at  first 
not  unpleasant,  afterward  nauseating  and  provocative  of  severe  headache.  It 
boils  at  131.4°,  and  crystallizes  at  — 20°;  sp.  gr.  0.8184  at  15°.  It  mixes  with 
alcohol  and  ether,  but  not  with  water.  It  burns  with  a  pale  blue  flame  when 
sufficiently  heated. 

When  exposed  to  air  it  oxidizes  very  slowly;  quite  rapidly,  however,  in 
contact  with  platinum-black,  forming  isovaleric  acid.  The  same  acid,  along 
with  other  substances,  is  produced  by  the  action  of  the  more  powerful  oxidants 
upon  amyl  alcohol.  Chlorine  attacks  it  energetically,  forming  amyl  chloride, 
C,HltCI,  and  other  chlorinated  derivatives.  Sulphuric  acid  dissolves  in  amyl 


ALCOHOLS  221 

alcohol,  with  formation  of  amyl-sulphuric  acid,  S04(CBHU)H,  corresponding  to 
ethyl-sulphuric  acid  (p.  277).  It  also  forms  similar  acids  with  phosphoric, 
oxalic,  citric,  and  tartaric  acids.  Its  esters,  when  dissolved  in  ethyl  alcohol, 
have  the  taste  and  odor  of  various  fruits,  and  are  used  in  the  preparation  of 
artificial  fruit-essences.  Amyl  alcohol  is  also  used  in  analysis  as  a  solvent,  par- 
ticularly for  certain  alkaloids,  and  in  pharmacy  for  the  artificial  production 
of  valeric  acid  and  the  valerates. 


_  \  / 

Diethyl  Carbinol  —  ^H3  _  £H2  "/CHOH  —  is  produced  by  the  action  of  a  mix- 
ture of  zinc  and  ethyl  iodide  on  ethyl  formate,  with  the  subsequent  addition 
of  H2O.  It  is  a  liquid  which  boils  at  116.5°. 

OTT  \ 
Methyl-propyl    Carbinol—  CH  _CH  _  ^3")CHOH—  a     liquid,     boiling    at 

118.5°,  obtained  by  the  hydrogenation  of  methyl  -propylic  acetone. 

Methyl-isopropyl  Carbinol—  ,CH  ,  _  ^3yCHOH  —  obtained  by  the  hydro- 
genation of  methyl-isopropylic  acetone;  or  by  the  action  of  hydriodic  acid  upon 
amylene,  and  the  action  of  moist  silver  oxide  upon  the  product  so  obtained. 
It  is  a  colorless  liquid,  sp.  gr.  0.829  at  0°,  having  a  pungent,  ethereal  odor; 
boils  at  112.5°,  soluble  in  H20  and  in  alcohol. 

Ethyl-dimethyl    Carbinol  —  Tertiary    amylic    alcohol  —  Amylene    hydrate  — 

CH3\ 
CH3—  CH2  —  COH  —  is   a   liquid   which   solidifies   at  —  12°,   and   boils   at    102.5°; 

CH3/ 

formed  by  the  action  of  zinc  methyl  upon  propionyl  chloride,  or  by  decomposi- 
tion of  tertiary  sulphamylic  acid  by  boiling  H20.  The  nitrite  of  this  alcohol 
has  been  used  as  a  substitute  for  amyl  nitrite. 

DIATOMIC,  OR  DIHYDRIC  ALCOHOLS;  GLYCOLS. 

The  paraffin  glycols  are  derived  from  the  paraffins  by  the  substi- 
tution of  two  hydroxyls  for  two  H  atoms.  They  bear  the  same  rela- 
tion to  the  monoatomic  alcohols  that  the  diacid  bases  bear  to  the 
monacid  bases.  They  are  diprimary,  disecondary,  primary-secondary, 
etc.,  according  as  they  contain  groups  CH2OH  ;  CHOH,  or  COH. 
Their  "Geneva"  names  are  derived  from  those  of  the  parent  hydro- 
carbons by  the  substitution  of  the  syllable  "dial"  for  the  terminal  e; 
and  they  are  distinguished  as  a,  fi,  y,  d,  etc.,  according  as  the  hy- 
droxyls occupy  1  :2,1  :3,1  :4,1  :5,  etc.,  positions.  Thus  the  primary- 
secondary  glycol  CH2OH.CH2.CHOH.CH3,  is  /?-butandiol. 

As  the  monohydric  alcohols  are  regarded  as  the  hydroxides  of  the 
univalent  alkyls,  so  the  dihydric  alcohols  are  considered  as  the  hy- 
droxides of  bivalent  hydrocarbon  radicals:  (CoH4)":(OH)2,  which  are 
called  alkylenes. 

They  may  be  obtained  from  the  neutral  haloid  esters  by  heating 
with  silver  acetate  : 

C2H4I2+  2AgC2H302=2AgI+C2H4  (  C2H302)  2 
And  saponification  of  the  ester  so  formed  by  caustic  potash  : 

C2H4  (  C2H302)  2-f  2KHO=C2H4  (  OH)  2+2KC2H302 
While  the  monoatomic  alcohols  are  only  capable  of  forming  a  sin- 


222  TEXT-BOOK   OF   CHEMISTRY 

gle  ester  with  a  monobasic  acid,  the  glycols  are  capable  of  forming 
two  such  esters: 

CH2  ( C2H302 ) '  CH2  ( C2H302 ) '  CH2  ( C2H302 ) ' 

CH3  CH2OH  CH2(C2H302)' 

Ethyl    acetate.  Moiioacetic    glycol.  Diacetic   glycol. 

Ethene  Glycol — Ethylene  glycol,  or  alcohol,  or  hydroxide — 
CH2OH 

— 62. — This,  the  best  known  of  the  glycols,  is  prepared  by  the 
CH2OH 

action  of  dry  silver  acetate  upon  ethylene  bromide.  The  ester  so 
obtained  is  purified  by  redistillation,  and  decomposed  by  heating  for 
some  time  with  barium  hydroxide. 

It  is  a  colorless,  slightly  viscous  liquid;  odorless;  faintly  sweet; 
sp.  gr.  1.125  at  0°;  boils  at  197°;  sparingly  soluble  in  ether;  very 
soluble  in  water  and  in  alcohol. 

It  is  not  oxidized  by  simple  exposure  to  air,  but  on  contact  with 
platinum-black  it  is  oxidized  to  glycolic  acid ;  more  energetic  oxidants 
transform  it  into  oxalic  acid.  Chlorine  acts  slowly  upon  glycol  in  the 
cold ;  more  rapidly  under  the  influence  of  heat,  producing  chlorinated 
and  other  derivatives.  By  the  action  of  dry  HC1  upon  cooled  glycol, 
a  product  is  formed,  intermediate  between  it  and  ethylene  chloride,  a 

CH2OH 
neutral  compound — ethene  chlorhydrine,     |          ,  which  boils  at  130°. 

Ditertiary  glycols  are  produced  by  the  action  of  organic  mag- 
nesium halides  upon  the  esters  of  dibasic  acids  in  the  same  manner  as 
tertiary  monohydric  alcohols  are  formed  from  those  of  monobasic 
acids  (p.  213). 

Pinacone  or  tetramethylethylene  glycol  is  a  ditertiary  alcohol 
produced  by  the  action  of  nascent  hydrogen  (sodium)  upon  acetone: 

2CH3.CO.CH3+H2=  ( CH3)  2  :COH.COH :  ( CH3)  2 

It  is  also  formed  by  the  successive  action  of  silver  acetate  and 
barium  hydroxide  on  hexylene  dibromide: 

( CH3)  2.CBr.CBr :  (CH.)  2+2CH3.COO.Ag=  (CH3)  2  :C  ( C2H302) . 

C(C2H302):(CHS)2  and 

(CH3)2:C(C2H302).(C2H302).C:(CH3)2+Ba(OH)2=(CH3)2: 
COH.COH.(CH3)2+Ba(C2H302)2 

It  is  also  produced  by  the  general  method,  by  the  action  of  mag- 
nesium methiodide  upon  ethyl  oxalate. 

TRIATOMIC,  OR  TRIHYDRIC  ALCOHOLS;  GLYCEROLS. 

These  are  derived  from  the  paraffins  by  the  substitution  of  three 
hydroxyls  for  three  hydrogen  atoms,  linked  to  different  carbon  atoms. 
The  simplest  triprimary  glycerol,  which  would  have  the  formula: 


ALCOHOLS  223 

CH(CH2OH)3,  is  unknown.  The  simplest  known  representative  of 
the  ^  class  is  the  ordinary  glycerine,  more  properly  called  glycerol, 
which  is  diprimary-secondary.  The  relations  of  the  monoatomic,  di- 
atomic, and  triatomic  alcohols  to  each  other  and  to  the  parent  hydro- 
carbon are  shown  in  the  following  formulae: 

CH8 


CH2 


CH3 

CH2OH 

CH2OH 

CH2 

bH2 

CHOH 

CH2OH 

CH2OH 

CH2OH 

Propyl    alcohol. 

Propyl   glycol. 

Glycerol. 

Propane, 

The  Geneva  names  of  the  glycerols  are  derived  from  those  of  the 
hydrocarbons  by  the  substitution  of  the  syllable  "triol"  for  the  ter- 
minal e.  Thus  glycerol  is  propantriol. 

They  are  obtained  by  the  saponification  of  their  esters,  either 
those  existing  in  nature  or  those  produced  artificially. 

They  combine  with  acids  to  form  three  series  of  esters,  known 
generically  as  monoglycerides,  diglycerides,  and  triglycerides, 
formed  by  the  combination  of  one  molecule  of  the  alcohol  with  one, 
two,  or  three  molecules  of  a  monobasic  acid.  The  names  of  the  in- 
dividual esters  terminate  in  in,  and  have  a  prefix  indicating  the  num- 
ber of  acid  residues.  Thus:  C3H5(OH)2.C2H302  is  monacetin, 
C3H5(OH)  (C2H302)2  is  diacetin,  and  C3H5(C2H302)3  is  triacetin. 

Glycerol  —  Glycerine  —  Propenyl  alcohol  —  Glycerinum  (U.  S.  P.) 
—  C3H5(OH)3  —  92  —  was  first  obtained  as  a  secondary  product  in  the 
manufacture  of  lead  plaster;  it  is  now  produced  as  a  by-product  in 
the  manufacture  of  soaps  and  of  stearin  candles.  It  exists  free  in 
palm-oil  and  in  other  vegetable  oils.  It  is  produced  in  small  quan- 
tity during  alcoholic  fermentation,  and  is  consequently  present  in 
wine  and  beer.  It  is  much  more  widely  disseminated  in  its  esters, 
the  neutral  fats,  in  the  animal  and  vegetable  kingdoms. 

It  has  been  obtained  by  partial  synthesis,  by  heating  a  mixture  of 
allyl  tribromide,  silver  acetate  and  acetic  acid,  and  saponifying  the 
triacetin  so  obtained.  Also  by  total  synthesis,  by  reduction  of  dioxy- 
acetone  by  sodium  amalgam  in  presence  of  aluminium  sulphate: 

CH2OH.CO.CH2OH+H2=CH2OH.CHOH.CH2OH 

Glycerol  obtained  by  saponification  of  fats,  and  purified  by  dis- 
tillation in  a  current  of  superheated  steam,  known  as  "  distilled  gly- 
cerine, vy  is  reasonably  pure.  The  only  impurities  likely  to  be  present 
are  water,  and  sometimes  arsenic. 

Glycerol  is  a  colorless,  odorless,  syrupy  liquid,  has  a  sweetish 
taste;  sp.  gr.  1.26  at  15°.  Although  it  cannot  usually  be  caused 
to  crystallize  by  the  application  of  the  most  intense  cold,  it  does  so 
sometimes  under  imperfectly  understood  conditions,  forming  small, 
white  needles  of  sp.  gr.  1.268,  and  fusible  between  17°  and  18°. 


224  TEXT-BOOK   OP   CHEMISTRY 

It  is  soluble  in  all  proportions  in  water  and  alcohol,  insoluble  in 
ether  and  in  chloroform.  It  is  a  good  solvent  for  a  number  of  mineral 
and  organic  substances  (glycerites  and  glyccroles).  It  is  not  volatile 
at  ordinary  temperatures.  When  impure  glycerol  is  heated,  a  por- 
tion distils  unaltered  at  275°-280°,  but  the  greater  part  is  decom- 
posed into  acrolein,  acetic  acid,  carbon  dioxide,  and  combustible  gases. 
It  may  be  distilled  unchanged  in  a  current  of  superheated  steam  be- 
tween 285°  and  315°.  Pure  glycerol  distils  unchanged  at  290°  at  a 
pressure  of  756  mm.,  and  at  180°  at  20  mm. 

Concentrated  glycerol,  when  heated  to  150°  ignites  and  burns 
without  odor  and  without  leaving  a  residue,  and  with  a  pale  blue 
flame.  It  may  also  be  burnt  from  a  short  wick. 

Glycerol  is  readily  oxidized,  yielding  different  products  with  dif- 
ferent degrees  of  oxidation.  Platinum-black  oxidizes  it,  with  forma- 
tion, finally,  of  H2O  and  C02.  Oxidized  by  manganese  dioxide  and 
H2S04,  it  yields  C02  and  formic  acid.  If  a  layer  of  glycerol  diluted 
with  an  equal  volume  of  H20  is  floated  on  the  surface  of  HN03  of  sp. 
gr.  1.5,  a  mixture  of  several  acids  is  formed :  oxalic,  C2H204 ;  glyceric, 
C3H604,  formic,  CH202;  glycollic,  C2H403;  glyoxylic,  C2H4O4;  and 
tartaric,  C4H(iO)5.  When  glycerol  is  heated  with  potassium  hydroxide, 
a  mixture  of  potassium  acetate  and  formate  is  produced.  When 
glycerol,  diluted  with  20  volumes  of  H20,  is  heated  with  Br;  C02, 
bromoform,  glyceric  acid,  and  HBr  are  produced.  Phosphoric  anhy- 
dride removes  the  elements  of  H20  from  glycerol,  with  formation  of 
acrolein  (p.  330).  A  similar  action  is  effected  by  heating  with 
H2S04,  or  with  monopotassic  sulphate.  Heated  with  oxalic  acid, 
glycerol  yields  C02  and  formic  acid. 

The  presence  of  glycerol  in  a  liquid  may  be  detected  as  follows : 
Add  NaOH  to  feebly  alkaline  reaction,  and  dip  into  it  a  loop  of  Pt 
wire  holding  a  borax  bead ;  then  heat  the  bead  in  the  blow-pipe  flame, 
which  is  colored  green  if  the  liquid  contain  Moo  of  glycerol. 

The  glycerol  used  for  medicinal  purposes  should  respond  to  the 
following  tests:  (1)  its  sp.  gr.  should  not  vary  much  from  that  given 
above;  (2)  it  should  not  rotate  polarized  light;  (3)  it  should  not  turn 
brown  when  heated  with  sodium  nitrate;  (4)  it  should  not  be  colored 
by  H2S;  (5)  when  dissolved  in  its  own  weight  of  alcohol,  containing 
one  per  cent,  of  H2S04,  the  solution  should  be  clear;  (6)  when  mixed 
with  an  equal  volume  H2S04,  of  sp.  gr.  1.83,  it  should  form  a  limpid, 
brownish  mixture,  but  should  not  give  off  gas. 

POLYATOMIC,  OR  POLYHYDRIC  ALCOHOLS. 

Tetratomic  Alcohols  contain  four  hydroxyls.     The  best  known  is: 
Erythrol -—Erythritc — CH2OH.  ( CHOH )  a.CH2OH— which   is  a  product  of  de- 
composition   of    erythrin,    ('..,,H  .,()„,,    which    exists   in    the    lichens   of   the    ^enus 
rnrrlln.      It    crystiilli/cs   in    Inr^e,   brilliant    prisms;    very    soluble    in    H,<)   and    in 
hot  alcohol,  almost   insoluble   in  ether;    sweetish    in   taste;    its   solutions   neither 


ALDEHYDES   AND   KETONES  225 

affect  polarized  light,  nor  reduce  Fehling's  solution,  nor  are  capable  of  fermen- 
tation. Its  watery  solution,  like  that  of  sugar,  is  capable  of  dissolving  a  con- 
siderable quantity  of  lime,  and  from  this  solution  alcohol  precipitates  a  definite 
compound  of  erythrite  and  calcium.  By  oxidation  with  platinum-black  it  yields 
erythroglucic  acid,  C4H8O5.  With  fuming  HN03  it  forms  a  tetranitro  com- 
pound, which  explodes  under  the  hammer. 

Pentatomic,  or  Pentahydric  Alcohols — Pentites — contain  five  hydroxyls. 
The  only  member  of  the  group  known  to  exist  in  nature  is  the  simplest 
C5H7(OH)5,  called  adonite,  obtained  from  Adonis  vernalis.  Other  members  of 
the  series  are  obtained  by  reduction  of  the  corresponding  aldopentoses. 

Hexatomic,  or  Hexahydric  Alcohols — Hexites — contain  six  hydroxyls. 
They  are  closely  related  to  the  sugars,  which  they  resemble  in  their  properties, 
although  they  do  not  reduce  Fehling's  solution,  and  are  not  fermented  by 
yeast.  They  are  obtained  by  reduction  of  the  corresponding  glucoses,  aldo- 
hexoses  and  ketohexoses.  Three  hexites  occur  in  nature: 

Mannitol— Mannite — CH2OH.  ( CHOH )  4.CH2OH — constitutes  the  greater  part 
of  manna,  and  also  exists  in  a  number  of  other  plants.  It  is  also  produced 
during  the  so-called  mucic  fermentation  of  sugar,  and  during  lactic  fermenta- 
tion. It  crystallizes  in  long  prisms,  odorless,  sweet;  fuses  at  166°  and  crystal- 
lizes on  cooling;  boils  at  200°,  at  which  temperature  it  is  converted  into 
mannitan,  C6Hi2O5;  soluble  in  H2O,  very  sparingly  in  alcohol. 

Sorbitol — Sorbite — occurs  in  mountain-ash  berries.  It  forms  crystals, 
soluble  in  water. 

Dulcitol — Dulcite — Melampyrite — Dulcose — Dulcin — exists  in  melampyrum 
nemorosum.  It  forms  colorless,  transparent  prisms,  fuses  at  182°,  is  odorless, 
faintly  sweet,  neutral  in  reaction,  and  optically  inactive.  It  is  subject  to  de- 
compositions very  similar  to  those  to  which  mannite  is  subject,  yielding 
dulcitan,  C6H12O5. 

Heptatomic,  Octatomic  and  Nonatomic  Alcohols,  containing  respectively 
seven,  eight  and  nine  hydroxyls,  are  also  known. 

All  polyatomic  alcohols  in  solutions  alkalized  with  caustic  soda,  when 
agitated  with  benzoyl  chloride,  form  insoluble  benzoic  esters,  and,  under  proper 
conditions,  the  separation  is  quantitative,  a  fact  which  is  utilized  for  their 
separation.  The  diamines  behave  similarly  with  benzoyl  Chloride. 

ALDEHYDES  AND  KETONES. 

The  pure  aldehydes  and  ketones,  containing  only  CHO  or  CO  and 
hydrocarbon  groups,  are  to  be  considered  rather  as  the  second  prod- 
ucts of  oxidation  of  the  paraffins  than  as  the  first  products  of  oxi- 
dation of  the  alcohols,  primary  or  secondary.  While  the  distinction 
is  not  material  with  the  aldehydes  derivable  from  the  monoatomic 
alcohols,  it  is  so  with  similar  derivatives  of  alcohols  of  higher  atom- 
icity and  with  the  ketones,  which  may  be  either  pure  aldehydes  or 
ketones,  or,  if  they  retain  alcoholic  groups,  substances  of  mixed 
function:  aldehyde-alcohols  and  ketone-alcohols.  Thus  from  the 
hydrocarbons  the  following  may  be  derived : 

2  ( CH3.CH3 )  -j-Oa=2  ( CH3.CH2OH )  Alcohols— CMH2n+ 2O, 

CH3.CH3-f02=H20+CH3.CHO  —  Aldehydes— CnH2nO, 

CH3.CH3-f  202=2H20+CHO.CHO  Glyoxals— CwH2r?_  202, 

CH3.CH2.CH3+02=H20+CH3.CO.CH3  =  Kc-tones— CnH2nO, 

and  from  the  alcohols  not  only  the  above,  but  also  substances  such  as 


226  TEXT-BOOK   OF   CHEMISTRY 

2  (  CH2OH.CH2OH  )  -f02=2H2O-|-2  (  CHO.CH2OH  )  =Glycolyl  aldehyde, 

2  (  CH2OH.CHOH.CH2OH  )  -f-O2=2H2O+2  (  CHO.CHOH.CH2OH  )  =Glycerol  aldehyde, 

2  (  CH2OH.CHOH.CH2OH  )  +O2=2H20-f  2  (  CH2OH.CO.CH2OH  )  =Glycerol   ketone. 

The  aldehydes  and  ketones  are  isomeric  with  each  other  and  also 
with  the  alkyl  alcohols,  CH2:CH.CH2OH,  and  the  methylene  oxides, 
* 


Both  aldehydes  and  ketones  contain  the  carbonyl  group  CO,  which 
in  the  ketone  is  united  to  two  alkyls,  CH3.CO.CH3  ;  and  in  the  alde- 
hyde to  one  alkyl  and  a  hydrogen  atom,  CH3.CO.H. 

Because  of  the  presence  of  this  oxygen  atom,  doubly  linked  to 
carbon,  both  aldehydes  and  ketones  form  addition  products  with 
hydrogen,  the  former  to  produce  primary,  and  the  latter  secondary 
alcohols  : 

CH3.CHO+H2=CH3.CH2OH,  and 
CH3.CO.CH3+H2=CH3.CHOH.CH3. 

The  aldehydes,  in  which  the  C:0:  is  in  a  terminal  group,  also 
form  other  addition  products  mentioned  below. 

Aldehydes  and  ketones  are  acted  upon  by  phosphorus  penta- 
chloride  to  form  compounds  in  which  oxygen  is  replaced  by  the 
halogen.  Thus  acetic  aldehyde  yields  ethidene  chloride,  or  dichlor- 
ethane. 

CH3.CHO+PC15=:CH3.CHC12+POC13 

And  acetone  yields  ft  dichlorpropane  : 

CH3.CO.CH3+PC15=CH3.CC12.CH3+POC13 

Aldehydes  and  ketones  are  acted  upon  by  alkyl  magnesium  halides 
to  produce  secondary  and  tertiary  alcohols  (p.  290). 

All  aldehydes  and  ketones  condense  with  hydroxylamine  to  form 
oximes  (p.  320)  : 

CH3.CHO+NH2.OH=CH3.CH  :N.OH+H20 

and  with  phenylhydrazine  to  form  hydrazones  and  osazones  (p.  380). 
Both  of  these  reactions  are  extensively  used  for  the  identification  of 
substances  containing  the  C:0:  group. 

The  aldehydes  and  ketones  may  be  considered  as  derivatives  of 
formic  aldehyde,  0  :C(^,  alkyls  being  substituted  for  one  H  atom  only 

in  the  aldehydes:  0:C/^H»,  and  for  both  in  the  ketones:  0:C<^ 

ALDEHYDES. 

The  name  "  aldehyde"  is  a  contraction  of  "alcohol  dehydrogen- 
atum,"  derived  from  the  method  of  formation  of  these  bodies  by 
removal  of  hydrogen  from  alcohol. 

The  aldehydes  are  formed:  (1)  By  the  limited  oxidation  of  the 
corresponding  alcohols: 

2CH3.CH2OH+02=2CH3.CHO+2H20 


ALDEHYDES   AND   KETONES  227 

(2)  'By  the  action  of  nascent  hydrogen  upon  the  corresponding 
acidyl  chlorides  or  anhydrides: 

CH3.CO.C1+H,=CH3.CHO+HC1,  or 
(CH3.CO)20+2H2=2CH3.CHO+H20 

(3)  By  the  distillation  of  a  mixture  of  calcium  formate  and  the 
Ca  salt  of  the  corresponding  acid: 

(H.COO)  2Ca+  (CH3.COO)  2Ca=2C03Ca+2CH3.CHO 

(4)  By  the   action   of  alkyl   magnesium  halides  upon   primary 
amides,  and  hydrolysis  of  the  product.     Thus  propionic  aldehyde  is 
produced  from  acetamide  : 

H2N.CO.CH3+CH3.Mg.Br.=H2N.CH,.CH(CH3).O.Mg.Br  and 
H2N.CH2.CH(CH3).O.Mg.Br.+H20=NH3+CH3.CH2CHO+ 

HO.Mg.Br. 

With  formamide  secondary  reactions  occur,  but  with  its  bisub- 
stituted  derivatives,  R2N.CHO,  the  formation  of  aldehydes  proceeds 
normally. 

The  aldehydes,  being  intermediate  between  the  alcohols  and  acids, 
are  readily  converted  into  the  former  by  the  action  of  reducing  agents  : 

CH3.CHO+H2=CH3.CH2OH 
Or  into  the  latter  by  oxidation: 

2CH3.CHO+02=2CH3.COOH 

The  facility  with  which  the  aldehydes  are  oxidized  renders  them 
active  reducing  agents. 

They  combine  with  the  monometallic  alkaline  sulphites  to  form 
crystalline  compounds,  whose  formation  is  frequently  resorted  to 
for  their  separation  and  purification: 

CH3.CHO+S03HNa=CH3.CH(^Na 

They  unite  directly  with  ammonia  to  produce  crystalline  com- 
pounds called  aldehyde  ammonias  (p.  319)  : 


CH3.CHO+NH3=CH3CH 

Chlorine  and  bromine  displace  the  hydrogen  of  the  aldehydic 
group  with  formation  of  acidyl  chlorides  or  bromides: 

CH3.CHO+C12=CH3.CO.C1+HC1 

The  oxygen  of  the  same  group  may  be  displaced  by  chlorine,  by 
the  action  of  phosphorus  pentachloride,  with  formation  of  paraffin 
dichlorides  : 

CH3.CHO+PC15=CH3.CHC12+POC13 

By  indirect  means  compounds  may  be  also  obtained  in  which  the 
hydrogen  of  the  hydrocarbon  group  is  substituted  by  chlorine,  as 
chloral  is  obtained  from  ethylic  alcohol  : 


228  TEXT-BOOK   OF    CHEMISTRY 

CH8.CH2OH+4C12=CC13.CHO+5HC1 

The  aldehydes  polymerize  readily,  forming  cyclic  compounds,  as 
trioxymethylene  is  formed  by  formic  aldehyde: 


Or  two  aldehyde  molecules  may  condense,  by  union  through  car- 
bon atoms,  to  form  oxyaldehydes,  as  aldol  is  formed  by  condensa- 
tion of  acetic  aldehyde: 

2CH3.CHO=CH3.CHOH.CH2.CHO 

Hydrocyanic  acid  combines  with  the  aldehydes  (and  ketones)  to 
produce  oxycyanides,  or  nitriles  of  the  oxyacids  : 


which,  in  turn,  are  decomposable  by  acids  or  alkalies  with  forma- 
tion of  the  ^-oxyacids. 

Methanal  —  Formaldehyde  —  H.CHO  —  30  —  is  formed  when  air 
charged  with  vapor  of  methylic  alcohol  is  passed  over  an  incan- 
descent platinum  wire.  It  is  also  produced  by  the  dry  distillation  of 
calcium  formate: 

(H.COO)  2Ca=CaC03+H.COH 

By  strong  cooling,  it  condenses  to  a  colorless  liquid,  which  boils 
at  —  21  °.  It  has  a  sharp,  penetrating  odor,  and  is  an  active  germi- 
cide. It  is  extensively  used  as  an  antiseptic  and  disinfectant,  either 
in  the  gaseous  form  or  in  aqueous  solution.  The  commercial  forma- 
line is  a  40  per  cent,  solution. 

Formic  aldehyde  is  probably  produced  as  an  intermediate  product 
in  plant  nutrition,  when  carbon  dioxide  is  decomposed  by  the  green 
pigment,  chlorophyll,  under  the  influence  of  sunlight,  with  liberation 
of  oxygen:  C02H-H20=II.CHO+02,  and  when  so  produced  it  may 
readily  polymerize  to  form  hexoses  (p.  237)  :  6H.CHO=C6H1200. 

Formaldehyde  polymerizes  with  great  readiness  by  moderate  eleva- 
tion of  temperature  to  form  paraformaldehyde,  or  trioxymethylene, 
°\CH8'o/CH»»  which  is  also  obtained  as  a  crystalline  substance, 
fusing'  at  152°,  insoluble  in  H20,  alcohol  and  ether,  by  distilling 
glycollic  acid  with  H2S04,  or  by  the  action  of  silver  oxalate  or  oxide 
on  methene  iodide:  CH2I2+Ag20=H.CHO+2AgL 

Formic  aldehyde  reacts  with  a  great  variety  of  substances,  and.  in 
reactions  at  elevated  temperatures  may  advantageously  be  replaced  by 
the  solid  trioxymethylene,  which  is  then  dissociated.  Like  all  alde- 
hydes (and  it  is  doubly  an  aldehyde:  0  :C<£J|[),  it  is  an  active  reduc- 
ing agent.  With  caustic  alkalies  it  forms  methyl  alcohol  and  a  for- 
mate: 

2H.CHO+NaOH=H.CH2OH+H.COONa 

Or,  in  the  presence  of  CuO,  a  formate  ami  hydrogen: 
H.CHO+NaOH=:H.COONa+lL 


ALDEHYDES  AND   KETONES  229 

Calcium  hydroxide  and  other  basic  hydroxides,  by  prolonged  con- 
tact, cause  its  polymerization  to  formose:  6H.CHO=C6H1206.  With 
ammonia  it  forms  hexamethylene  tetramine;  and  with  ammoniacal 
salts  it  forms  a  variety  of  complex  amines  and  nitriles. 

An  extremely  valuable  property  of  formic  aldehyde  is  the  facility 
with  which  it  parts  with  its  oxygen  atom,  by  reason  of  which  it 
readily  enters  into  condensations,  uniting  other  molecule-remainders 
through  the  bivalent  group  CH2. 

A  condensation  is  the  formation  of  a  new  molecule  by  the  union 
of  the  remainders  of  two  or  more  others,  with  the  splitting  off  of 
water,  alcohol,  or  some  other  substance.  A  condensation  differs 
from  a  polymerization  in  that  in  the  latter  nothing  is  split  off,  and 
all  the  substances  involved  are  polymeres  of  each  other.  Sometimes 
condensations  are  effected  by  simple  contact  of  the  reacting  substances 
at  more  or  less  elevated  temperatures;  but,  more  usually,  the  pres- 
ence of  another  substance,  acting  as  a  contact  agent,  is  required. 
Substances  acting  in  this  manner  are  quite  numerous,  and  are  called 
condensing  agents.  Probably  the  most  important  are  aluminium, 
ferric  and  zinc  chlorides,  hydrochloric  and  sulphuric  acids,  sodium 
acetate  and  ethylate,  pyridine,  and  piperidine. 

As  examples  of  the  simplest  condensations  with  formic  aldehyde 
we  may  mention  the  two  following:  With  alcohols  it  condenses  to 
produce  f ormals : 

2H.CH2OH+H.CHO=CH3.O.CH2.O.CH3+H20 

With  secondary  amines  it  condenses  to  form  alkyl  diamines: 

2R'2NH+H.CHO=R'2N.CH2.NR'2+H20 

an    action    which    is    particularly    marked    with    aromatic    amines: 
2C6H5NH2+H.CHO=C6H5.NH.CH2.NH.C6H5+H20 

Other  instances  of  the  condensing  action  of  formic  aldehyde  will 
be  considered  later. 

The  presence  of  formic  aldehyde,  which  is  now  frequently  added  to  milk 
and  other  articles  of  food,  may  be  recognized  by  the  following  reactions,  after 
distillation,  if  necessary:  (1)  Heat  with  0.5  cc.  dimethylaniline  and  a  few  drops 
H2S04  on  the  water-bath  for  half  an  hour;  add  excess  of  alkali;  expel  excess 
of  dimethylaniline  with  a  current  of  steam;  filter;  place  the  filter  in  a  porcelain 
capsule  and  moisten  it  with  acetic  acid;  add  a  trace  of  lead  peroxide,  and 
warm:  an  intense  blue  color.  (2)  Add  the  liquid  (distillate)  to  an  equal  volume 
of  aqueous  solution  of  aniline  (3:1000):  a  white  ppt.  (3)  Dissolve  0.01  mor- 
phine hydrochloride  in  1  cc.  concentrated  H2S04,  and  mix  two  drops  of  this 
and  suspected  solutions:  an  intense  rose-violet  color. 

Ethanal— Acetaldehyde— Acetic    Aldehyde— CH3.CHO  —  44— is 

formed  in  all  reactions  in  which  alcohol  is  deprived  of  H  without 
introduction  of  0.  It  is  prepared  by  distilling  from  a  capacious  re- 
tort, connected  with  a  well-cooled  condenser,  a  mixture  of  H2S04, 


230  TEXT-BOOK   OF   CHEMISTRY 

6  pts. ;  H20,  4  pts. ;  alcohol,  4  pts.,  and  powdered  manganese  dioxide, 
6  pts.  The  product  is  redistilled  from  calcium  chloride  below  50°. 
The  second  distillate  is  mixed  with  two  volumes  of  ether,  cooled  by  a 
freezing  mixture,  and  saturated  with  dry  NH3;  there  separate  crys- 
tals of  aldehyde  ammonia,  CH3.CH^Q£2,  which  are  washed  with 
ether,  dried  and  decomposed  in  a  distilling  apparatus,  over  the  water- 
bath,  with  the  proper  quantity  of  dilute  H2S04 ;  the  distillate  is  finally 
dried  over  calcium  chloride  and  rectified  below  35°. 

Acetic  aldehyde  is  also  formed  by  heating  acetylene  with  vapor  of 
water : 

CH:CH+H20=CH3.CHO 

Aldehyde  is  a  colorless,  mobile  liquid;  has  a  strong,  suffocating 
odor;  sp.  gr.  0.790  at  18°;  boils  at  21°;  soluble  in  all  proportions 
in  water,  alcohol  and  ether.  If  perfectly  pure,  it  may  be  kept  un- 
changed; but  if  an  excess  of  acid  has  been  used  in  its  preparation, 
it  gradually  decomposes.  When  heated  to  100°  it  is  decomposed  into 
water  and  crotonic  aldehyde: 

2CH3.CHO=CH3.CH  :CH.CHO+H20 

In  the  presence  of  nascent  H,  aldehyde  takes  up  H2,  and  regen- 
erates alcohol.  Cl  converts  it  into  acetyl  chloride,  C2H3O.C1,  and 
other  products.  Oxidizing  agents  convert  it  into  acetic  acid.  At 
the  ordinary  temperature  H2S04;  HC1;  and  S02  convert  it  into  a 
colorless  liquid  called  paraldehyde  (C2H40)3,  which  boils  at  124°, 
and  is  more  soluble  in  cold  than  in  warm  water.  The  same  reagents, 
acting  upon  aldehyde  at  temperatures  below  0°  convert  it  into 
metaldehyde  (C2H40)n.  When  heated  with  potassium  hydroxide, 
aldehyde  becomes  brown,  a  brown  resin  separates,  and  the  solution 
contains  potassium  formate  and  acetate. 

Vapor  of  aldehyde,  when  inhaled  in  a  concentrated  form,  produces  asphyxia, 
even  in  comparatively  small  quantity.  When  diluted  with  air  it  is  said  to 
act  as  an  anesthetic.  When  taken  internally  it  causes  sudden  and  deep  in- 
toxication, and  it  is  to  its  presence  that  the  first  products  of  the  distillation 
of  spirits  of  inferior  quality  owe  in  a  great  measure  their  rapid,  deleterious 
action. 

Trichloraldehyde— Chloral— CC13.CHO— 147.5— is  one  of  the  final 
products  of  the  action  of  Cl  upon  alcohol,  and  is  obtained  by  passing 
dry  Cl  through  absolute  alcohol  to  saturation;  applying  heat  toward 
the  end  of  the  reaction,  which  requires  several  hours  for  its  com- 
pletion. The  liquid  separates  into  two  layers;  the  lower  is  removed 
and  shaken  with  an  equal  volume  of  concentrated  H2S04  and  again 
allowed  to  separate  into  two  layers ;  the  upper  is  decanted ;  again 
mixed  with  H2S04,  from  which  it  is  distilled ;  the  distillate  is  treated 
with  quicklime,  from  which  it  is  again  distilled,  that  portion  which 
passes  over  between  94°  and  99°  being  collected.  It  sometimes  hap- 


ALDEHYDES   AND   KETONES  231 

pens  that  chloral  in  contact  with  H2S04  is  converted  into  a  modifica- 
tion; insoluble  in  H2O,  known  as  metachloral  ;  when  this  occurs  it  is 
washed  with  H20,  dried  and  heated  to  180°,  when  it  is  converted 
into  the  soluble  variety,  which  distils  over. 

The  formation  of  chloral  from  alcohol  does  not  progress  according 
to  the  simple  equation: 

CH3.CH2OH+4C12=CC13.CHO+5HC1 

but  passes  through  several  stages.  First,  the  alcohol  is  oxidized 
to  aldehyde  : 

CH3.CH2OH+C12=CH3.CHO+2HC1 

This  reacts  with  alcohol  to  produce  acetal: 

CH3.CHO+2CH3.CH2OH=CH3.CH(OC2H5)2+H20 

This  is  then  converted  into  trichloracetal  : 

CH3CH(OC2H5)2+3C12=CC13.CH(OC2H5)2+3HC1 

This,  by  the  action  of  the  hydrochloric  acid  formed  in  the  last 
reaction,  yields  chloral  alcoholate  and  ethyl  chloride: 


And  from  the  former  chloral  is  liberated  by  sulphuric  acid  : 
CC13.CH  ^oxU.  +H2S04=:CC13.CHO+  (  C2H5)  HS04+H20 

Chloral  is  a  colorless  liquid,  unctuous  to  the  touch;  has  a  pene- 
trating odor  and  an  acrid,  caustic  taste;  sp.  gr.  1.502  at  18°,  boils  at 
97°,  very  soluble  in  water,  alcohol,  and  ether;  dissolves  Cl,  Br,  I,  S, 
and  P.  Its  vapor  is  highly  irritating.  It  distils  without  alteration. 

Although  chloral  has  not  been  obtained  by  the  direct  substitution 
of  Cl  for  H  in  aldehyde,  its  reactions  show  it  to  be  an  aldehyde.  It 
forms  crystalline  compounds  with  the  bisulphites  ;  it  reduces  solutions 
of  silver  nitrate  in  the  presence  of  NH3  ;  with  nascent  H  it  regen- 
erates aldehyde;  oxidizing  agents  convert  it  into  trichloracetic  acid. 
Alkaline  solutions  decompose  it  with  formation  of  chloroform  and 
a  formate: 

CC13.CHO+KOH=CHC13+H.COOK 

With  a  small  quantity  of  H20  chloral  forms  a  solid,  crystalline 
hydrate,  heat  being  at  the  same  time  liberated.  This  hydrate  has  the 
composition  C2HC13O.H20,  and  its  constitution,  as  well  as  that  of 
chloral  istelf,  is  indicated  by  the  formulae: 

CH3  CC13  CC13 

CHO  CHO  CH(OH)2 

Aldehyde.  Trichloraldehyde  Chloral  hydrate. 

(chloral). 

Chloral  Hydrate—  -Chloralum  hydratum—  Chloral—  (U.  S.  P.)— 
is  a  white,  crystalline  solid  ;  fuses  at  57  °  ;  boils  at  98  °,  at  which  tem- 
perature it  suffers  partial  decomposition  into  chloral  and  H.,0; 


232  TEXT-BOOK   OF   CHEMISTRY 

volatilizes  slowly  at  ordinary  temperatures;  is  very  soluble  in  H20; 
neutral  in  reaction  ;  has  an  ethereal  odor,  and  a  sharp,  pungent  taste. 
Concentrated  H2S04  decomposes  it,  with  formation  of  chloral  .and 
chloralide,  C5H2C1603.  [chloralide,  or  chloraldide  is  trichlorethidene 

trichloracetic    ester:    CC13.CH/°QO)CH  c^     IINo3    converts    it 

into  trichloracetic  acid.  When  pure  it  gives  no  precipitate  with  silver 
nitrate  solution,  and  is  not  browned  by  contact  with  concentrated 
H2S04.  Under  the  influence  of  sunlight  it  is  violently  decomposed 
by  potassium  chlorate,  which  oxidizes  it  in  part  to  trichloracetic 
acid;  chlorine,  phosgene  gas,  carbon  dioxide,  and  chloroform  are 
given  off,  and  after  a  time,  crystals  of  potassium  trichloracetate  sep- 
arate from  the  cooled  mixture. 

Chloral    also    combines    with    alcohol,    with    elevation    of    tem- 
perature,   to    form   a    solid,    crystalline    body  —  chloral    alcoholate: 

on 

ui 


Action  of  Chloral  Hydrate  upon  the  Economy.  —  Although  it  was  the 
ready  decomposition  of  chloral  into  a  formate  and  chloroform  which  first  sug- 
gested its  use  as  a  hypnotic  to  Liebreich,  and  although  this  decomposition  was 
at  one  time  believed  to  occur  in  the  body  under  the  influence  of  the  alkaline 
reaction  of  the  blood,  more  recent  investigations  have  shown  that  the  formation 
of  chloroform  from  chloral  in  the  blood  is,  to  say  the  least,  highly  improbable, 
and  that  chloral  has,  in  common  with  many  other  chlorinated  derivatives  of 
this  series,  the  property  of  acting  directly  upon  the  nerve-centers. 

Neither  the  urine  nor  the  expired  air  contains  chloroform  when  chloral  is 
taken  internally;  and  when  taken  in  large  doses,  chloral  appears  in  the  urine. 
The  fact  that  the  action  of  chloral  is  prolonged  for  a  longer  period  than  that 
of  the  other  chlorinated  derivatives  of  the  fatty  series  is  probably  due,  in  a 
great  measure,  to  its  less  volatility  and  less  rapid  elimination. 

When  taken  in  overdose,  chloral  acts  as  a  poison;  a  strong  aqueous  solu- 
tion is  frequently  added  by  criminals  to  intoxicants  to  deprive  their  victims  of 
consciousness  (knock-out  drops). 

No  chemical  antidote  is  known.  The  treatment  should  be  directed  to  the 
removal  of  any  chloral  remaining  in  the  stomach  by  the  stomach  tube,  and  to 
the  maintenance  or.  restoration  of  respiration. 

In  fatal  cases  of  poisoning  by  chloral  that  substance  may  be  detected  in  the 
blood,  urine,  and  contents  of  the  stomach  by  the  following  method:  the  liquid 
is  rendered  strongly  alkaline  with  potassium  hydroxide:  placed  in  a  flask,  which 
is  warmed  to  50°-60°,  and  through  which  a  S!O\Y  current  of  air,  heated  to  the 
same  temperature,  is  made  to  pass;  the  air,  after  bubbling  through  the  liquid, 
is  tested  for  chloroform  by  the  methods  described  on  p.  206.  As  chloral  distils 
with  vapor  of  water  from  acid  solutions,  and  as  it  gives  the  same  reactions  as 
chloroform,  except  that  with  the  resorcinol  reaction  it  gives  a  brilliant  green 
fluorescence  (p.  207),  the  presence  of  chloral  as  such  can  only  be  positively 
demonstrated  by  extraction  of  the  crystals  of  the  hydrate  by  ether,  and  spon- 
taneous evaporation  of  the  ethereal  solution. 

Acetals  —  Formals.  —  These  are  ester-like  bodies  corresponding  to  the  hypo- 
thetical aldehyde  hydrates:  CH3.CH/Q^,  which  are  themselves  incapable  of 

/OTT 
existence,  except  they  contain  a  halogen,  as  in  chloral  hydrate:  CCla.CH^  QJJ 


KETONES   OR  ACETONES  233 

The  acetals  have  the  general  formula:  R'.CH'f  QR,'  and  the  formals  the  struc- 
ture^: CH2/Q£,'  in  which  R'  represents  an  alkyl.  The  acetals  are  produced  by 
oxidation  of  the  alcohols  by  MnO2  and  H2S04.  Thus 

6CH3.CH2OH-f  02=:2CH3.CH  ( OC2H5 )  2+4H2O, 

and  by  other  methods.  The  formals  are  formed  by  condensation,  in  presence 
of  H2S04,  or  of  FeCl3,  of  alcohols  and  formic  aldehyde: 

2CH3.CH2OH+H.CHO=CH3.CH2.O.CH2.O.CH2.CH3+H20. 

The  formation  of  acetals  and  formals  is  utilized  in  the  preparation  of 
certain  aldehydes,  such  as  glyceric  aldehyde.  By  hydrolyzing  agents,  as  by 
heating  with  aqueous  HC1,  they  are  split  into  their  components: 

CH3.CH  ( O.C2H5 )  24-H2O=CH3.CHO-f-2CH3.CH2OH. 

/OC*TT 
Methylal— Formal — CH2\QCH3~76 — is  formed  b^  distilling  a  mixture  of 

Mn02  methyl  alcohol,  H2S04  and  H2O.  It  is  a  colorless  liquid;  sp.  gr.  0.8551 
at  17°;  boiling  at  42°;  soluble  in  H20,  alcohol,  and  oils.  It  has  a  burning, 
aromatic  taste,  and  an  odor  resembling  those  of  chloroform  and  acetic  acid. 
It  has  been  used  as  a  hypnotic. 

Acetal— CH3.CH<^Q£2j    —104— a    colorless    liquid,    boils    at    104°,    sp.    gr. 

0.8314;  sparingly  soluble  in  H2O,  readily  in  alcohol;  obtained  by  heating  a 
mixture  of  aldehyde,  alcohol  and  glacial  acetic  acid,  or  in  the  same  manner  as 
formal,  using  ethylic  in  place  of  methylic  alcohol. 

Dialdehydes — containing  two  CHO  groups,  such  as  Glyoxal — 
CHO.CHO,  are  also  known.  Glyoxal  is  formed  by  the  limited  oxida- 
tion of  acetic  aldehyde  by  nitric  acid: 

CH3.CHO+02=CHO.CHO+H20 

But  it  has  not  been  obtained  pure,  containing  oxalic  and  formic 
acids  as  impurities.  It  is  very  soluble  in  water,  and  has  the  chemical 
properties  common  to  the  aldehydes. 

KETONES  OR  ACETONES. 

The  ketones,  or  acetones,  contain  the  group  C  :0,  linking  two 
hydrocarbon  groups;  or  they  may  be  considered  as  derived  from  the 
hydrocarbons  by  substitution  of  0  for  H2  in  a  CH2  group.  The  mono- 
ketones  contain  one  CO  group,  the  diketones  two,  etc.  The  (CO)" 
group  also  occurs  in  the  aldehydes,  in  which,  however,  it  is  linked 
with  H,  (0:C.H)',  and  in  the  carboxyl  group,  in  which  it  is  linked 
with -OH,  (OiC.OH)',  in  both  cases  occupying  a  terminal  position 
with  reference  to  other  C  atoms,  while  in  ketones,  ketonic  acids,  etc., 
its  position  is  intermediate.  Ketones  are  symmetrical  if  the  two 
alkyls  united  by  CO  are  similar,  unsymmetrical  if  they  are  different : 

CH8 
CH3 


CO 
60 


COOH  CO  | 

CH3  CH3 

CH3 

Acetic    Acid.  Dimethyl   ketone          Methyl-ethyl    ketone. 

(acetone). 


234  TEXT-BOOK    OF    CHEMISTRY 

Ketones  are  isomeric  with  and  closely  allied  to  the  aldehydes,  from 
which  they  differ  chiefly  in  that:  (1)  They  are  not  so  easily  oxidized, 
do  not  reduce  alkaline  solutions  of  silver  salts,  and,  on  oxidation, 
split  at  the  CO  group  to  form  a  carboxylic  acid  or  acids,  or  ketones, 
of  less  carbon  content: 

CH3.CO.CH3+202=CH3.COOH:+C02+H20 

(2)  Nascent  hydrogen  converts  them  into  secondary  alcohols  by 
addition : 

CH3.CO.CH3+H2=CH3.CHOH.CH3 

(3)  The  ketones  do  not  polymerize. 

(4)  Only  those  ketones  which  contain  a  methyl  group  form  crys- 
talline compounds  with  alkaline  bisulphites. 

The  monoketones  are  produced:  (1)  By  oxidation  of  the  secondary 
alcohols : 

2CH3.CHOH.CH3+02=2CH3.CO.CH3+2H20 

(2)  By  distillation  of  the  calcium  salts  of  the  fatty  acids: 

Ca(CH3.COO)2=CH3.CO.CH3+CaC03 

(3)  By  decomposition  of  ketonic  acids: 

CH3.CO.CH2.COOH=C02+CH3.CO.CH3 

(4)  By  the  interaction  of  zinc  alkyls  and  acidyl  halides : 

Zn(CH3)2+2CH3.CO.Cl=2CH3.CO.CH3+ZnCl2 

(5)  By  the  action  of  sodium  upon  a  mixture  of  acidyl  and  alkyl 
halides : 

CH3.CO.Cl+CH3I+Na2=CH3.CO.CH3+NaCl+NaI. 

(6)  By  the   action  of  alkyl   magnesium  halides  upon   primary 
amides,  and  hydrolysis  of  the  product,  the  reactions  being  three  in 
number.    First,  a  condensation: 

CH3.CO.NH2+2CH3.Mg.Br=  ( CH3)  2  :C  (NH.Mg.Br )  .O.Mg.Br+CH4 

Second,  the  hydrolysis  of  this  with  the  formation  of  an  oxyamine 
(p.  296)  : 

(CH3)2:C(NH.Mg.Br).O.Mg.Br+2H20=(CH3)2:C<^  + 

MgBr2+Mg02H2 

And,  finally,  the  deamidation  of  the  oxyamine : 

(CH3)2:C(OH)  =CH3.CO.CH3+NH3 

(7)  By  the  action  of  alkyl  magnesium  halides  upon  nitriles,  and 
hydrolysis  of  the  products: 

CH,.Mg.Br+CH3.CN=  ( CH3)  2  :C  :N.MgBr  and 
(CH3)  2  :C  :N.Mg.Br+2H20=CH3.CO.CH3+NH3+HO.MgBr 

Acetone  —  Dimethyl  Ketone  —  Propanon  —  CO/^ "~  58  ~  is 
formed  as  one  of  the  products  of  the  dry  distillation  of  the  acetates; 
by  the  decomposition  of  the  vapor  of  acetic  acid  at  a  red  heat;  by 


CARBOHYDRATES  235 

the  dry  distillation  of  sugar,  tartaric  acid,  etc.  ;  and  in  a  number  of 
other  reactions.    It  is  obtained  by  distilling  dry  calcium  acetate: 
CH3.COO\p, 


It  is  also  formed  in  large  quantity  in  the  preparation  of  aniline. 

It  is  a  limpid,  colorless  liquid;  sp.  gr.  0.921  at  18°;  boils  at  56°; 
soluble  in  H20,  alcohol  and  ether;  has  a  peculiar  ethereal  odor  and 
a  burning  taste;  is  a  good  solvent  of  resins,  fats,  camphor,  gun- 
cotton;  readily  inflammable.  It  forms  crystalline  compounds  with 
the  alkaline  bisulphites.  Cl  and  Br,  in  the  presence  of  alkalies,  con- 
vert it  into  chloroform  or  bromoform  ;  Cl  alone  produces  with  acetone 
a  number  of  chlorinated  products  of  substitution.  Certain  oxidizing 
agents  transform  it  into  a  mixture  of  formic  and  acetic  acids;  others 
into  oxalic  acid. 

Acetone  has  been  found  to  exist  in  the  blood  and  urine  in  certain 
pathological  conditions,  and  notably  in  diabetes.  The  peculiar  odor 
exhaled  by  diabetics  is  produced  by  this  substance,  which  has  also 
been  considered  as  being  the  cause  of  the  respiratory  derangements 
and  coma  which  frequently  occur  in  the  last  stage  of  the  disease. 

That  acetone  exists  in  the  blood  in  such  cases  is  certain  :  it  is  not 
certain,  however,  that  its  presence  produces  the  condition  designated 
as  acetonemia.  It  can  hardly  be  doubted  that  the  acetone  thus  ex- 
isting in  the  blood  is  indirectly  formed  from  diabetic  sugar,  and  it  is 
probable  also  that  a  complex  acid,  known  as  ethyldiacetic,  C6H903H, 
is  formed  as  an  intermediate  product. 

See  aromatic  ketones. 

Diketones,  containing  two  CO  groups,  such  as  CH3.CO.CO.CH3, 
triketones,  such  as  CH3.CO.CO.CO.CH3,  and  tetraketones,  such  as 
CH3.(CO)4.CH3,  are  also  known. 

CARBOHYDRATES. 

The  definition  of  the  term  carbohydrate  as  "a  substance  of  un- 
known constitution  composed  of  carbon,  hydrogen  and  oxygen,  in 
which  the  oxygen  and  hydrogen  are  in  the  same  proportion  as  in 
water"  was  self-destructive  so  soon  as  the  constitution  of  these  sub- 
stances should  become  known,  as  it  now  has.  Yet  the  first  words  of 
the  definition  were  necessary  to  exclude  substances  such  as  acetic 
acid,  C2H402,  which  would  otherwise  accord  with  the  '  definition,  yet 
were  never  considered  as  carbohydrates.  But,  while  the  sugars  and 
starches  have  been  thus  removed  from  the  "miscellaneous"  residuum 
of  our  chemical  classification,  they  are  still  conveniently  referred  to 
as  carbohydrates  in  physiological  chemistry. 

The  simplest  of  the  carbohydrates  are  oxyaldehydes  or  ketols  in 
which  all  the  groups,  other  than  the  aldehyde  or  ketone  groups,  are 
primary  or  secondary  alcoholic  groups;  and  the  more  complex  con- 
sist of  two  or  more  molecules  of  the  simpler  forms,  united  with 
elimination  of  water. 


236 


TEXT-BOOK   OF    CHEMISTRY 


The  carbohydrates  are  classified  into: 

Monosaccharides,  or  Monoses — which  do  not  yield  any  other 
sugar  or  sugars  by  the  action  upon  them  of  dilute  acids  (glucose, 
fructose,  galactose,  etc.)  ; 

Disaccharides,  or  Saccharobioses — which,  under  the  influence  of 
dilute  acids,  take  up  H.,0  and  yield  two  other  sugar  molecules  (sac- 
charose, lactose,  maltose,  etc.)  ; 

Trisaccharides,  or  Saccharotrioses — which,  under  the  same  in- 
fluence, take  up  2H20  and  yield  three  other  sugar  molecules;  and 

Polysaccharides — which,  under  the  same  influence,  take  up  more 
than  2H20,  and  yield  more  than  three  sugar  molecules  (starches, 
gums,  celluloses,  etc.). 

The  disaccharides,  trisaccharides,  and  polysaccharides  may  be  con- 
sidered as  produced  by  the  fusion  of  two  or  more  monosaccharide 
molecules  with  elimination  of  one  or  more  molecules  of  water. 

Those  carbohydrates  which  contain  the  ketone  group,  CO,  are 
called  ketoses,  those  containing  the  aldehyde  group,  CHO,  aldoses. 
The  names  of  all  carbohydrates  terminate  in  ose- 

MONOSACCHARIDES— MONOSES. 

Monosaccharides  are  dioses,  trioses,  tetroses,  pentoses,  hexoses, 
heptoses,  octoses  or  nonoses  according  as  they  contain  from  two  to 
nine  carbon  atoms.  (See  table  below.) 

The  monosaccharides  are  neutral  substances,  sweet,  odorless,  white, 
insoluble  in  ether,  sparingly  soluble  in  alcohol,  and  readily  soluble  in 
water.  Like  all  aldehydes  and  ketones,  they  are  readily  oxidized,  and 
in  their  oxidation  act  as  reducing  agents.  It  is  upon  this  quality  that 
the  several  "reduction  tests/'  such  as  Trommer's,  Fehling's, 
Boettger's,  etc.,  are  based.  Another  quality  of  the  monosaccharides, 
utilized  for  their  separation  and  identification,  is  that  they  all  give 
crystalline  precipitates  of  substances  called  osazones  when  their 
solutions,  acidulated  with  acetic  acid,  are  heated  with  phenyl- 
hydrazine,  C0H5H  :N.N  :H2.  The  trioses,  hexoses  and  nonoses  are 
capable  of  alcoholic  fermentation,  the  others  are  not. 

Aldoses. 
CHO         CHO          CHO  CHO  CHO  CHO  CHO  CHO 

CH2OH     OTOH     (CHOH)2   (CHOH)3  (CHOH)4   (CHOH)8  (CHOH)a    (CHoil    , 


»        CHO 
DH     CHOH 
CH2OH 

Ketoses. 
CH2OH 

Jo 

CH2OH 

CHO 
(CHOH) 
CH2OH 

CH2OH 

io 

CHOH 

CH2OH       CH2OH       CH2OH       CH2OH        CH2 


H,OH 


CH2OH       CH2OH 

CO  CO 

I 


CH2OH 

c'o 


CH2OH 

Jo 


CH2OH 
00 


HOH       (CHOH)2   (CHOH),   (CHOH)4   (CHOH).     (CHOH). 


HOH)4   (CHOH)B     (Cl 


CH2 


OH       CH,( 


CH2OH 


CH2OH       CH2OH        CH2 


OH 


Dioses.         Trloses.         Tetroses.        Pentoses.          Hexoses.          Ileptoses.         Octoses.         Nonoses. 


CARBOHYDRATES  237 

DIOSES,  TRIOSES,  TETROSES  AND  PENTOSES. 

Glycolyl  aldehyde,  CH^OH.CHO.  is  the  only  diose  possible.  It  is  produced 
by  the  action  of  baryta  water  upon  brom-acetaldehyde. 

Of  the  two  possible  trioses  Glyceric  aldehyde  is  obtained  by  starting  from 
acrolein  acetal.  This  is  oxidized  to  glyceric  acetal: 

2CH2 :  CH.CH  ( O.C2HC )  2+202+2H20=2CH2OH.CHOH.CH  ( O.CaH5 ) , ; 
which  is  then  hydrolyzed : 

CH2OH.CHOH.CH  ( O.C2H5 )  24-H2O=CH2OH.CHOH.CHO4-2CH3.CH2OH. 

Glycerol  ketone,  or  dioxyacetone,  CH2.OH.CO.CH,OH,  has  also  been  ob- 
tained synthetically.  The  aldehyde  and  ketone  are  formed  together  when  glycerol 
is  oxidized  by  dilute  nitric  acid. 

Similarly  erythrose  is  a  mixture  of  the  two  tetroses,  CHO.(CHOH)2.CIL,OH 
and  CH2OH.CHOH.CO.CH2OH,  formed  by  oxidation  of  erythrol  by  dilute  nitric 
acid. 

The  pentoses  hitherto  described  are  all  aldo-pentoses,  C4H5- 
(OH)4.CHO,  although  keto-pentoses  probably  also  exist.  When  dis- 
tilled with  hydrochloric  or  dilute  sulphuric  acid  they  yield  furfurole : 

/CH:CH 

CHO.(CHOH)3.CH2OH=3H,0+CHO.C  / 

\\  CH.O 

a  reaction  which  is  utilized  for  their  quantitative  determination. 
Arabinose  is  a  pentose  obtained  by  the  action  of  dilute  sulphuric 
acid  upon  cherry  gum.  Xylose,  or  wood  sugar,  is  produced  by 
boiling  wood-gum  with  dilute  acid.  Ribose  is  a  synthetic  product. 
Rhamnose,  or  Isodulcite,  Chinovose,  and  Fucose  are  methyl-pen- 
toses:  CH3(CHOH)4.CHO,  obtained  by  the  decomposition  of  certain 
glucosides  or  from  sea  weeds.  These  pentoses  result  from  the  hy- 
drolysis of  pcntosancs,  polysaccharides  occurring  as  gums  in  plants. 
Pentoses  have  also  been  found  in  the  urine,  particularly  in  diabetes 
and  after  the  use  of  certain  fruits  containing  pentosanes.  They  are 
also  among  the  products  of  decomposition  of  certain  nucleoproteids. 
Pentoses,  when  warmed  with  hydrochloric  acid  in  presence  of  phloro- 
glucin,  give  a  fine  red  color,  and  a  sharp  absorption  band  near  the 
Na  line. 

HEXOSES— GLUCOSES. 

In  this  class  are  included  some  well-known  sugars,  such  as  glucose 
and  fructose,  which  occur  free  in  the  vegetable  world.  They  exist  in 
ether-like  combination  in  many  of  the  glucosides. 

They  are  mostly  sweet,  crystalline  substances,  very  soluble  in 
water,  and  difficultly  soluble  in  alcohol.  They  are  formed  by  (1)  the 
hydrolysis  of  the  di-  and  polysaccharides: 

C12H2Ai+H20=2CflH12Ofl 

(2)  By  oxidation  of  the  corresponding  hexatomic  alcohol. 

(3)  By  reduction  of  the  lactones  of  the  monocarboxylic  acids. 
They  exhibit  the  usual  reactions  of  the  alcohols  and  those  of  the 

aldehydes  or  ketones.    On  reduction  they  produce  hexatomic  alcohols ; 


238  TEXT-BOOK   OF   CHEMISTRY 

and  on  oxidation  they  yield  monocarboxylic  acids.  Their  alcoholic 
hydrogen  is  replaceable  by  certain  metals  with  formation  of  sacchar- 
ates,  corresponding  to  the  alcoholates.  With  acids  they  yield  esters. 
They  form  osazones  with  phenylhydrazine.  Some  are  very  prone 
to  alcoholic  fermentation: 

C6H1206=2C2H60+2C02 

while  others  readily  undergo  lactic  fermentation  : 

C6H1206=2C3H603 

Being  polyatomic  alcohols,  the  hexoses  form  insoluble  benzoic 
esters  when  their  alkaline  solutions  are  shaken  with  benzoyl  chloride. 

Of  the  described  hexoses,  mannose,  glucose,  gulose.  idose.  galac- 
tose  and  talose  are  aldoses;  fructose  and  sorbinose  are  ketoses. 

Optical  Activity.  —  All  of  the  hexoses  exi>t  in  three  isomerides,  differing 
from  each  other  in  their  action  upon  polarized  light.  One  of  these  rotates  the 
plane  of  polarization  to  the  right,  and  is  designated  as  the  dextro-,  or  d-com- 
pound;  another  is  laevogyrous  and  is  designated  as  the  laevo-,  or  1-compound, 
while  the  third  is  inactive,  and  is  distinguished  by  the  symbol  (d- 

Stereoisomcrism,  or  Space  Isomerism.—  The  graphic  formula  indicate  the 
structure  of  the  molecule  only  partially;  they  .show  that  certain  atoms  in  the 
molecule  are  attached  to  some  of  their  fellows  more  closely  than  to  others, 
but  they  give  no  indication  of  the  positions  which  the  atoms  occupy  in  space 

H\ 
with  regard  to  each  other.     The  expression          C  —  O  —  H,  the  most  completely 


detailed  graphic  representation  of  that  group,  indicates  at  the  most  that  the 
two  hydrogen  atoms  are  attached  to  one  side  of  the  carbon  atom,  while  the 
hydroxyl  is  attached  to  another.  Stereochemistry  is  that  branch  of  cheni 
treating  of  the  relations  of  the  atoms  to  each  other  in  space.  It  has  been 
greatly  developed  in  recent  years  and  affords,  among  other  things,  the  first 
rational  explanation  of  the  cause  of  the  differences  in  the  optical  activity  of  the 
hexoses,  as  well  as  of  lactic  and  tartaric  acids,  and  of  many  other  substances. 

If  we  suppose  that  differences  in  the  relative  positions  which  atoms  or 
groups  attached  to  carbon  atoms  occupy  with  relation  to  each  other  produce 
different  compounds  (see  Place  Isomerism,  p.  260,  Orientation,  p.  337);  and  if 
we  also  suppose  that  the  four  valences  of  the  carbon  atom  act  in  a  plane  and 
at  right  angles  to  each  other,  a  vast  number  of  space-isomerides  of  the  di-  and 
poly-substituted  derivatives  of  the  aliphatic  hydrocarbons  would  exist,  no  rep- 
resentatives of  which  are,  however,  known.  For  example,  marsh-gas  would 
yield  two  isomerides  of  each  of  the  types:  CH2X,,  CH2XY  and  CH  X  \.  and 
three  isomerides  of  the  type  CHXYZ,  in  which  X,  Y,  and  Z  represent  any 
three  univalent  atoms  or  radicals,  thus: 

H  H  H  H  H  H 

Cl—  (!—  Cl,  Cl—  C—  H,  Br—  C—  Cl,  H—  C—  Cl,  Cl—  C—  Cl,  Cl—  C—  Br; 


d  1 


i         B,       c, 

Type    CH,X,  Type   CH,XY.  Tjpe   CHX,Y. 

H  H  H 

Cl—  C—  I,  I—  C—  Br,  and  Br—  C—  Cl 

i 

CHXYZ. 


d, 


CARBOHYDRATES 


239 


8 


Bu€  only  one  representative  of  each  of  these  types  is  known.  Therefore 
the  usual  graphic  representation  of  the  valences  of  the  carbon  atom  as  above, 
white  convenient,  is  not  spatially  consistent  with  fact,  and  the  four  valences  of 
the  carbon  atom  are  not  exerted  in  one  plane. 

The  suggestion  of  Van't  Hoff  (following  the  somewhat  similar  idea  of 
Kekule")  that  the  valences  of  the  carbon  atom  are  represented  by  considering 
it  as  occupying  the  interior  of  a  regular  tetrahedron,  the  solid  angles  of  which 
indicate  the  direction  of  its  valences  (Fig.  18,  A),  taken  in  connection  with 
the  hypothesis  of  an  asymmetric  carbon  atom,  affords  a  rational  explanation 
of  the  facts  just  cited,  and  of  the 
differences  in  the  optical  proper- 
ties of  the  substances  mentioned. 

Admitting  the  regular  tetra- 
hedron to  represent  the  arrange- 
ment of  the  valences  of  the  carbon 
atom,  it  follows  that  all  carbon 
atoms,  two  of  whose  valences  are 
satisfied  by  the  same  kind  of  uni- 
valent  atom  or  group,  and  the 
other  two  by  two  constant  but 
dissimilar  univalents,  must  be 
symmetrical.  The  two  similar 
univalents  must  occupy  the  sum- 
mits at  the  extremities  of  some 
one  crest,  and  the  only  possible 
variation  in  arrangement  of  the 
other  two  is  in  their  position  with 
regard  to  this  crest.  Thus  B  and 
C,  Fig.  18,  although  dissimilar 
in  the  position  in  which  they  are 
placed,  become  perfectly  sym- 
metrical when  either  one  is  ro- 
tated through  180  degrees.  But 
when  all  four  of  the  carbon 
valences  are  satisfied  by  different 
univalents  two  arrangements  are 
possible,  producing  two  molecular 
groups  which  are  unsymmetrical 
in  whatever  position  they  may  be 
placed.  Thus  D  and  E,  Fig.  18, 
are  unsymmetrical  in  the  positions 
in  which  they  are  represented,  and 
remain  so.  however  their  positions 
may  be  changed.  A  carbon  atom 
attached  to  four  different  uni- 
valents is  called  an  asymmetric  carbon  atom.  In  graphic  formulae  asymmetric 
carbon  atoms  are  designated  by  the  italic  C,  or  by  an  asterisk,  C*.  Substances 
containing  an  asymmetric  carbon  atom  exist  in  three  optical  isomeres: 
dextrogyrous  (d),  la'royi/rons  (1),  and  optically  inactive,  or  racemic  (d-fl  or 
i,  or  r). 

The  structure  of  the  four  isomerie  tartaric  acids  was  first  explained  under 
the  hypothesis  of  the  asymmetric  carbon  atom.  Let  it  be  assumed  that  two 
asymmetric  carbon  atoms,  with  their  attached  groups  or  atoms,  exert  a  "di- 
recting influence"  upon  each  other,  and  that,  being  attached  to  each  other  at 
one  point  only,  they  are  capable  of  rotating  independently  about  a  common 
axis  (a.  a.  Fig.  18,  G),  such  rotation  would  then  occur  in  obedience  to  the 


gucH.on, 


240  TEXT-BOOK   OF   CHEMISTRY 

directing  influence  until  a  condition  of  equilibrium  is  reached,  in  which  position 
the  atoms  would  remain.  Assuming  this  position  to  be  that  shown  in  F,  G, 
and  H,  Fig.  18,  with  the  two  COOH  groups  in  like  relation,  then  the  three 
unsymmetrical  arrangements  shown  in  the  figure  arc  possible.  The  lirst  rep- 
resents the  structure  of  dextro-tartaric  acid,  G  that  of  laevo-tartaric  acid,  and 
H  that  of  meso-tartaric  acid,  while  racemic  acid  is  a  combination  of  dextro- 
and  laevo-tartaric  acids. 

The  tetrahedron  representation  of  the  carbon  valences  adapts  itself  well 
also  to  the  explanation  of  certain  isomerides  of  the  ethylene  series,  in  which 
two  carbon  atoms  are  doubly  linked  together.  In  these  Hie  two  carbon  atoms 
being  linked  together  at  two  points  (I  and  K,  Fig.  18)  cannot  be  considered  as 
being  capable  of  rotation,  and,  if  tbe  two  other  valences  of  each  carbon  are 
satisfied  by  the  same  two  dissimilar  univalents,  two  positions  are  possible: 
I,  in  which  the  like  univalents  are  directed  to  the  same  side,  called  the  "plane 
symmetrical  configuration,"  and  K,  in  which  they  are  directed  towards  opposite 
sides,  called  the  "  axially  symmetrical  configuration." 

Formose  is  a  synthetic  hexose,  obtained  by  polymerization  of  formic 
aldehyde : 

6H.CHO=CeH12O0 

Acrose  is  similarly  obtained  from  glyceric  aldehyde: 

2CH,OH.CHOH.CHO=C6H12O6 
or  by  the  action  of  barium  hydroxide  upon  acrolein  bromide: 

2CH2Br.CHBr.CHO+2Ba  ( OH )  2=C6H12O6+ 2BaBr2 

Mannose  is  obtained,  as  d-,  1-,  and  d+1,  mannoses  by  oxidation  of  the  cor- 
responding mannitols. 

Glucose  —  Grape  Sugar  —  Dextrose  —  Liver  Sugar  —  Diabetic 
Sugar — d-Glucose  occurs  in  many  sweet  fruits  and  vegetable  juices, 
and  in  honey,  accompanied  by  fructose ;  and,  in  the  animal  world,  in 
the  contents  of  the  intestine,  liver,  bile,  thymus,  heart,  lungs,  blood, 
and,  in  small  quantity,  in  the  urine.  Pathologically,  it  appears  in  the 
saliva,  perspiration,  feces,  and,  in  largely  increased  amount,  in  the 
blood  and  urine  in  diabetes  mellitus.  It  is  produced  by  the  decom- 
position of  the  polysaccharides  and  of  many  of  the  glucosides,  and  is 
manufactured  on  a  large  scale  by  the  action  of  boiling  dilute  H2S04 
upon  starch.  The  commercial  product  so  obtained  is  either  an  amor- 
phous, white  solid  (grape  sugar),  containing  about  60%  of  true  glu- 
cose, along  with  dextrins  and  the  unfermentable  isomaltose,  or 
gallisin,  C12H22On ;  or  a  thick,  colorless  syrup  (glucose),  containing, 
besides  the  above,  a  minute  quantity  of  a  nitrogenous  body  which 
exerts  a  solvent  action  upon  coagulated  albumin  at  the  body  tem- 
perature. 

d-Glucose  has  been  produced  synthetically  by  the  reduction  of  the 
lactone  of  d-gluconic  acid. 

It  crystallizes  from  its  aqueous  solutions  at  the  ordinary  tempera- 
ture with  difficulty  in  white,  opaque,  spheroidal  masses  containing 
1A<|.  which  fuse  at  86°  and  lose  the  Aq  at  110°.  From  its  concen- 
trated aqueous  solution  at  30°  to  35°,  or  from  its  alcoholic  solution  it 
crystallizes  in  hard,  anhydrous,  crystalline  crusts,  which  fuse  at  146°. 


CARBOHYDRATES  241 

It  is  soluble  in  all  proportions  in  hot  water,  is  very  soluble  in  cold 
water,  and  soluble  in  alcohol.  It  is  less  sweet  and  less  soluble  than 
cane  sugar.  Its  aqueous  solutions  are  dextrogyrous :  [a]  D=:-j-52.6° 
in  boiled  solutions.  Freshly  prepared  cold  aqueous  solutions  have 
nearly  double  that  rotary  power  at  first,  the  value  of  [a]D  gradually 
falling  to  52.6°  in  about  twenty-four  hours.  Its  osazone,  d-.glucosa- 
zone,  crystallizes  in  needles,  fusible  at  205°.  Its  solutions  dissolve 
baryta  and  lime,  with  which,  as  with  potash,  soda,  and  the  oxides  of 
Pb  and  Cu,  it  forms  saccharates. 

l-Glucose  is  formed  by  reduction  of  the  lactone  of  1-gluconic  acid. 
It  is  in  all  respects  similar  to  d-glucose  except  that  it  fuses  at  143°, 
and  its  solutions  are  laevogyrous  [rt]D= — 51.4°. 

d+l-Glucose  is  formed  by  reduction  of  d+1-gluconic  lactone;  or 
by  union  of  d-  and  1-glucose.  Its  solutions  are  optically  inactive. 

Galactose  is  also  known  in  its  three  modifications.  d-Galactose  is  pro- 
duced by  the  hydrolysis  of  milk  sugar  and  of  certain  gums.  It  crystallizes  more 
readily  than  glucose,  is  very  sparingly  soluble  in  cold  alcohol,  has  a  specific 
rotary  power  of  [a}D  =-(-83.33°,  and  fuses  at  160°.  By  reduction  it  yields 
dulcite,  and  by  oxidation  galactonic  acid,  CH2OH.  (CHOH)4.COOH,  and  mucic 
acid,  COOH.(CHOH)4.COOH.  Cerebrose,  obtained  by  the  hydrolysis  of 
cerebrin,  a  constituent  of  nerve  tissue,  is  identical  with  galactose. 

Fructose — Levulose — a  ketohexose,  exists  in  the  three  modifications. 
d-Fructose — Fruit  sugar — forms  the  uncrystallizable  portion  of  the  sugar  of 
fruits  and  of  honey,  in  which  it  is  associated  with  glucose;  it  is  produced 
artificially  by  the  prolonged  action  of  boiling  water  upon  inulin,  a  polysac- 
charide;  also,  along  with  an  equal  quantity  of  glucose,  as  one  of  the  constitu- 
ents of  invert  sugar,  by  the  decomposition  of  cane  sugar;  and  from  d-glucosa- 
zone.  It  crystallizes  with  great  difficulty,  fuses  at  05°,  is  very  soluble  in 
water,  and  insoluble  in  absolute  alcohol.  Although  called  d-fructose,  because 
of  its  formation  from  d-glucosazone,  it  is  strongly  loevorotary:  [a]D=: — 71.4°. 
It  is  less  readily  fermentable  than  glucose,  which  it  equals  in  the  readiness  with 
which  it  reduces  cupropotassic  solutions.  With  phenylhydrazine  it  yields 
d-glucosazone  (p.  381). 

Sorbinose,  also  a  ketohexose,  occurs  in  the  berries  of  the  mountain  ash. 
It  does  not  ferment.  Its  osazone  fuses  at  164°. 

DISACCHARIDES— SACCHAROBIOSES. 

Disaccharides  consist  of  two  molecules  of  monosaccharides,  united 
with  elimination  of  H20.  So  far  as  is  known  they  are  all  derived 
from  the  hexoses,  and  their  formula  is  consequently  C^H^On.  They 
are  all  capable  of  yielding  two  hexose  molecules  by  hydrolysis: 

C1IHM0U+H,0=2C.H110. 

a  change  which  is  called  "inversion."  The  union  of  the  two 
monosaccharide  molecules  is  either  through  the  aldehyde,  ketone,  or 
alcoholic  groups.  Of  the  three  most  important  disaccharides,  sac- 
charose, lactose  and  maltose,  the  first  named  has  no  reducing  power, 
and  yields  no  osazone  with  phenylhydrazine.  It  therefore  contains 


242  TEXT-BOOK   OF   CHEMISTRY 

no  aldehyde  or  ketone  group.  When  heated  with  acetic  anhydride 
to  160°  it  forms  an  octacetyl  ester,  C12H1403(O.C2H30)8.  It  there- 
fore contains  eight  hydroxyls.  When  hydrolyzed  it  yields  d-glucose 
and  d-fructose  (laevogyratory).  From  the  above  facts  we  may  infer 
that  saccharose  is  derived  from  the  two  hexoses  named,  united 
through  the  aldehyde  and  ketone  groups,  a  constitution  which  may  be 
represented  by  the  f ormulae : 

CH2OH.CO.  ( CHOH )  2.CHOH.CH2OH  CHO.  ( CHOH )  4.CH2OH 

d-Fructose.  d-Glucose. 

OX  /O 


CH2OH.CH.  ( CHOH )  2.C.CH2OH.        CH.  ( CHOH )  4.CH2 
Saccharose. 

Lactose  and  maltose  both  cause  reduction  and  yield  osazones.  On 
hydrolysis  the  former  yields  d-glucose  and  galactose,  and  the  latter 
only  d-glucose.  They  each  consequently  retain  an  aldehyde  (or 
ketone)  group,  and  their  constitution  may  probably  be  represented 

thus: 

,0 


CH2OH.CHOH.CH.  ( CHOH )  2.CH.O.CH2.  ( CHOH )  4.CHO  and 

/0\ 

CHO.  ( CHOH  )4.CH2  CHa.(CHOH)4.CHO 

The  disaccharides  are  hydrolyzed  by  boiling  with  very  dilute 
acids,  or  even  with  water,  and  by  several  enzymes  such  as  diastase, 
emulsin,  invertin,  ptyalin,  trypsin  and  pepsin. 

Saccharose — Cane  Sugar — exists  in  many  roots,  fruits  and 
grasses,  and  is  produced  from  the  sugar-cane,  Saccharum  officinarum, 
sorghum,  Sorghum  saccharatum,  beet,  Beta  vulgaris,  and  sugar-maple, 
Acer  saccharinum. 

For  the  extraction  of  sugar  the  expressed  juice  is  heated  in  large  pans 
to  about  100°;  milk  of  lime  is  added,  which  causes  the  precipitation  of  albumin, 
wax,  calcic  phosphate,  etc. ;  the  clear  liquid  is  drawn  off,  and  "  delimed  "  by 
passing  a  current  of  CO2  through  it;  the  clear  liquid  is  again  drawn  off  and 
evaporated,  during  agitation,  to  the  crystallizing  point;  the  product  is  drained, 
leaving  what  is  termed  raw  or  muscovado  sugar,  while  the  liquor  which  drains 
off  is  molasses.  The  sugar  so  obtained  is  purified  by  the  process  of  "refining," 
which  consists  essentially  in  adding  to  the  raw  sugar,  in  solution,  albumin  in 
some  form,  which  is  then  coagulated;  filtering  first  through  canvas,  afterward 
through  animal  charcoal ;  and  evaporating  the  clear  liquid  in  "  vacuum-pans,"  at 
a  temperature  not  exceeding  72°,  to  the  crystallizing  point.  The  product  is 
allowed  to  crystallize  in  earthen  moulds;  a  saturated  solution  of  pure  sugar  i- 
poured  upon  the  crystalline  mass  in  order  to  displace  the  nncrystallfzable  sugar 
which  still  remains,  and  the  loaf  is  finally  dried  in  an  oven.  The  liquid  dis- 
placed as  above  is  what  is  known  as  sugar-house  syrup. 

Pure  sugar  should  bo  entirely  soluble  in  water;  the  solution  should 
not  turn  brown  when  warmed  with  dilute  potassium  hydroxide  solu- 


CARBOHYDRATES  243 

tion;  should  not  reduce  Fehling's  solution,  and  should  give  no  pre- 
cipitate with  ammonium  oxalate. 

Beet-sugar  is  the  same  as  cane-sugar,  except  that,  as  usually  met  with  in 
commerce,  it  is  lighter,  bulk  for  bulk.  Sugar-candy,  or  rock-candy,  is  cane- 
sugar  allowed  to  crystallize  slowly  from  a  concentrated  solution,  without  agi- 
tation. Maple-sugar  is  a  partially  refined,  but  not  decolorized  variety  of  cane- 
sugar. 

Saccharose  crystallizes  in  small,  white,  monoclinic  prisms;  or,  as 
sugar-candy,  in  large,  yellowish,  transparent  crystals;  sp.  gr.  1,606. 
It  is  very  soluble  in  water,  dissolving  in  about  one-third  its  weight 
of  cold  water,  and  more  abundantly  in  hot  water.  It  is  insoluble  in 
absolute  alcohol  or  ether,  and  its  solubility  in  water  is  progressively 
diminished  by  the  addition  of  alcohol.  Aqueous  solutions  of  cane- 
sugar  are  dextrogyrous,  [a]  D=-j-66.5°. 

When  saccharose  is  heated  to  160°  it  fuses,  and  the  liquid,  on  cooling, 
solidifies  to  a  yellow,  transparent,  amorphous  mass,  known  as  barley-sugar; 
at  a  slightly  higher  temperature,  it  is  decomposed  into  glucose  and  Isevulosan ;  at 
a  still  higher  temperature,  H2O  is  given  off,  and  the  glucose  already  formed  is 
converted  into  glucosan;  at  about  200°  the  evolution  of  H20  is  more  abundant, 
and  there  remains  a  brown  material  known  as  caramel,  or  burnt  sugar;  a 
tasteless  substance,  insoluble  in  strong  alcohol,  but  soluble  in  H2O,  or  in  aqueous 
alcohol,  and  used  to  communicate  color  to  spirits;  finally,  at  higher  tempera- 
tures, methyl  hydride  and  the  two  oxides  of  carbon  are  given  off;  a  brown  oil, 
acetone,  acetic  acid,  and  aldehyde  distil  over;  and  a  carbonaceous  residue 


If  saccharose  is  boiled  for  some  time  with  H20,  it  is  converted 
into  inverted  sugar,  which  is  a  mixture  of  glucose  and  fructose: 
C12H22011+H20=CaH1206+C6H1206 

With  a  solution  of  saccharose  the  polarization  is  dextrogyrous, 
but,  after  inversion,  it  becomes  lasvogyrous,  because  the  left-handed 
action  of  the  molecule  of  fructose  produced,  [a]D= — 71.4°,  is  only 
partly  neutralized  by  the  right-handed  action  of  the  glucose, 
[a]u=+52.60.  This  inversion  of  cane  sugar  is  utilized  in  the  test- 
ing of  samples  of  sugar.  On  the  other  hand,  it  is  to  avoid  its  occur- 
rence, and  the  consequent  loss  of  sugar,  that  the  vacuum-pan  is  used 
in  refining — its  object  being  to  remove  the  H20  at  a  low  temperature. 

With  potassium  chlorate,  sugar  forms  a  mixture  which  detonates 
when  subjected  to  shock,  and  which  deflagrates  when  moistened  with 
H2S04.  Concentrated  H2S04  blackens  it.  Dilute  HN03,  when  heated 
with  saccharose,  oxidizes  it  to  saccharic  and  oxalic  acids. 

When  moderately  heated  with  liquor  potassae,  cane-sugar  does  not 
turn  brown,  as  does  glucose;  but  by  long  ebullition  it  is  decomposed 
by  the  alkalies,  much  less  readily  than  glucose,  with  formation  of 
acids  of  the  fatty  series  and  oxalic  acid. 

With  the  bases,  saccharose  forms  definite  compounds  called  sue- 


244  TEXT-BOOK   OF    CHEMISTRY 

rates  (improperly  saccharates,  a  name  belonging  to  the  salts  of  sac- 
charic acid).  With  Ca  it  forms  five  compounds.  Calcium  hydroxide 
dissolves  readily  in  solutions  of  sugar,  with  formation  of  a  Ca  com- 
pound, soluble  in  H20,  containing  an  excess  of  sugar. 

During  the  process  of  digestion,  probably  in  the  small  intestine, 
cane-sugar  is  inverted. 

Lactose — Milk  Sugar — Saccharum  lactis  (U.  S.  P.) — occurs  in 
the  milk  of  the  mammalia,  in  the  amniotic  fluid  of  cows,  and  in  the 
urine  of  women  towards  the  end  of  gestation  and  during  lactation. 
It  may  be  obtained  from  skim-milk  by  coagulating  the  casein  with 
a  small  quantity  of  H2S04,  filtering,  evaporating,  redissolving,  de- 
colorizing with  animal  charcoal,  and  recrystallizing. 

It  forms  prismatic  crystals ;  sp.  gr.  1.53 ;  hard,  transparent, 
faintly  sweet,  soluble  in  6  parts  of  cold  and  2.5  parts  of  boiling 
H20 ;  soluble  in  acetic  acid ;  insoluble  in  alcohol  and  in  ether.  Its 
solutions  are  dextrogyrous  [a]  D  =-(-52.5°.  The  crystals,  dried  at 
100°,  contain  lAq,  which  they  lose  at  150°. 

Lactose  is  not  altered  by  contact  with  air.  Heated  with  dilute 
mineral  acids  or  with  strong  organic  acids,  it  is  converted  into  galac- 
tose.  HN03  oxidizes  it  to  mucic  and  oxalic  acids.  A  mixture  of 
HN03  and  H2S04  converts  it  into  an  explosive  nitro-compound. 
With  organic  acids  it  forms  esters.  With  soda,  potash  and  lime  it 
forms  compounds  similar  to  those  of  saccharose,  from  which  lactose 
may  be  recovered  by  neutralization,  unless  they  have  been  heated  to 
100°,  at  which  temperature  they  are  decomposed.  It  reduces  Fehl- 
ing's  solution,  and  reacts  with  Trommer's  test.  Its  osazone  fuses 
at  200°. 

In  the  presence  of  yeast,  lactose  is  capable  of  alcoholic  fermenta- 
tion, which  takes  place  slowly,  and,  as  it  appears,  without  previous 
transformation  of  the  lactose  into  glucose  and  galactose.  On  contact 
with  putrefying  proteins  it  enters  into  lactic  fermentation.  It  is 
converted  into  galactose  by  the  pancreatic  secretion. 

Maltose — is  formed,  along  with  dextrins,  during  the  conversion 
of  starch,  or  of  glycogen,  into  sugar  by  the  action  of  diastase  (in 
malting  grain),  and  of  the  enzymes  of  the  saliva  and  the  pancreatic 
juice.  It  is  also  an  intermediate  product  in  the  hydrolysis  of  starch 
by  dilute  sulphuric  acid.  Maltose  crystallizes  in  hard,  white  needles 
aggregated  into  crusts.  It  is  less  soluble  in  alcohol  than  is  glucose, 
and  has  a  much  higher  dextrogyratory  power  [a]D  =+137°.  It  re- 
duces Fehling's  solution.  It  is  hydmlyzed  by  boiling  with  dilute 
acids,  yielding  only  d-glucose.  It  is  fermentable.  Its  osazone  fuses 
at  206°.  Nitric  acid  oxidizes  it  to  d-saccharic  acid. 

Isomaltose — Gallisin — is  formed  along  with  maltose,  in  the  action  of 
diastase,  saliva,  or  pancreatic  juice,  or  of  boiling  dilute  acids,  on  starch,  and 
exists  in  beer  and  artificial  glucose.  It  is  also  formed  by  the  prolonged 
action  of  strong  1IC1  on  d-glucose.  It  is  very  soluble  in  water,  very  sweet, 


CARBOHYDRATES  245 

and  does  not  ferment,  or  does  so  very  slowly.     Its  osazone  forms  yellow  needles, 
which  fuse  at  150°,  and  are  rather  soluble  in  hot  water. 

TRISACCHARIDES. 

Several  members  of  this  group  have  been  obtained  from  different  vegetables. 
They  have  the  formula  C18H32016.  The  best  known  are  Raffinose,  or  Melitose, 
which  occurs  in  eucalyptus-manna,  in  cotton  seed,  and  in  beet-sugar  molasses; 
and  Melecitose,  from  the  manna  of  Pinus  larix. 

POLYSACCHARIDES. 

The  starches,  gums,  and  celluloses,  which  form  this  class,  have 
the  empirical  formula  C6H1005,  but  their  molecular  weights  are  much 
greater  than  that  represented  by  that  formula.  They  are  very  widely 
distributed  in  vegetable  nature.  On  hydrolysis  they  are  finally  de- 
composed to  monosaccharides,  for  the  most  part  hexoses,  although 
some  of  the  gums  yield  pentoses. 

Starch — Amylum — the  most  important  member  of  the  group,  ex- 
ists in  the  roots,  stems,  and  seeds  of  all  plants ;  and  is  obtained  com- 
mercially from  rice,  potatoes,  and  maize.  It  is  a  white  powder,  con- 
sisting of  granules  which  are  round,  ovoid  or  irregular  in  outline, 
and,  in  some  cases,  marked  with  a  central  spot  or  line)  called  the 
hilum,  and  with  concentric  rings.  Differences  in  the  shape,  size  and 
markings  of  the  granules  are  utilized  to  identify  the  vegetable  from 
which  the  starch  was  obtained.  Air-dried  starch  contains  18%  of 
water,  of  which  it  loses  8%  in  vacuo,  and  the  remainder  only  at  145°. 
Starch  is  insoluble  in  cold  water  and  in  alcohol.  If  15  to  20  parts 
of  H20  are  gradually  heated  with  one  part  of  starch,  the  granules 
swell  at  about  55°,  and  at  80°  they  have  lost  their  structure,  have 
swelled  to  thirty  times  their  original  volume,  and  have  formed  a 
homogeneous,  translucent,  gelatinous  mass,  commonly  known  as 
starch  paste.  This  hydrated  starch  consists  of  an  insoluble  portion, 
starch  cellulose,  and  a  soluble  portion,  granulose,  or  soluble  starch. 
Granulose  forms  an  opalescent  solution  in  water,  from  which  it  is 
precipitated  as  a  white  powder  by  alcohol.  Its  solutions  are  strongly 
dextrogyrous,  [aJD=+207°  (about).  By  prolonged  boiling  with 
water,  or,  more  rapidly,  by  boiling  dilute  mineral  acids,  or  by  the 
action  of  diastatic  enzymes,  soluble  starch  is  converted  into  dextrins, 
maltose,  and  finally,  d-glucose.  Dry  heat  causes  the  starch  granules 
to  burst,  with  formation  of  dextrin.  A  dilute  solution  of  iodine 
produces  a  violet-blue  color  with  starch,  whether  dry,  hydrated,  or 
in  solution.  The  color  is  discharged  by  heat,  but  reappears  on  cool- 
ing. Concentrated  HN03  dissolves  starch  in  the  cold,  forming  a 
nitro-product,  called  xylodin,  or  pyroxam,  which  is  insoluble  in 
water,  soluble  in  a  mixture  of  alcohol  and  ether,  and  explosive. 

Glycogen — Animal  Starch — occurs  in  the  liver,  the  placenta, 
white  blood  corpuscles,  pus  cells,  young  cartilage  cells,  muscular 
tissue  and  many  embryonic  tissues,  also  in  many  molluscs.  It  is 


246  TEXT-BOOK   OF   CHEMISTRY 

best  obtained  from  liver  tissue,  by  extraction  with  hot  water  and 
precipitation  by  alcohol,  after  separation  of  protein  bodies  by  potas- 
sium iodhydrargyrate  and  acetic  acid.  It  is  a  snow-white,  floury 
powder,  amorphous,  tasteless,  and  colorless;  soluble  in  water,  forming 
an  opalescent  solution,  insoluble  in  alcohol  or  ether.  Its  solutions 
are  strongly  dextrogyrous,  [a]D  =-f-196.6°.  Glycogen  is  converted 
into  dextrins,  maltose,  and,  ultimately,  d-glucose  by  the  action  of 
boiling  dilute  acids,  and  by  the  salivary,  pancreatic  and  hepatic 
diastatic  enzymes.  Glycogen  is  colored  wine-red  by  iodine,  the  color 
being  discharged  by  heat  and  returning  on  cooling.  Its  solutions 
dissolve,  but  do  not  reduce  cupric  hydroxide. 

Other  starches  are:  Paramylum,  occurring  in  certain  infusoria; 
Lichenin,  in  lichens  and  mosses;  and  Inulin,  in  the  roots  of  dahlia, 
chicory  and  other  plants. 

Gums — are  amorphous,  translucent  substances  occurring  in  many 
plants.  They  are  insoluble  in  alcohol  and  in  ether.  With  water  some 
of  them,  the  true  gums,  form  clear  solutions ;  while  others,  the  vege- 
table mucilages,  swell  up  to  sticky  masses  which  cannot  be  filtered 
through  paper.  On  boiling  with  dilute  H2S04  the  gums  yield 
d-glucose,  galactose,  or  1-arabinose.  Nitric  acid  oxidizes  them  to 
mucic,  oxalic  and  saccharic  acids. 

The  commoner  members  of  the  group  are :  Arabin,  the  chief  con- 
stituent of  gum  arabic  (acacia)  and  gum  Senegal;  and  Bassorin,  the 
chief  ingredient  of  gum  tragacanth,  Bassora  gum,  and  plum  and 
cherry  gums. 

Dextrin — British  gum — a  substance  resembling  gum  arabic  in 
appearance  and  in  many  properties,  is  obtained  by  one  of  three 
methods:  (1)  by  subjecting  starch  to  a  dry  heat  of  175°;  (2)  by 
heating  starch  with  dilute  H2S04  to  90°  until  a  drop  of  the  liquid 
gives  only  a  wine-red  color  with  iodine;  neutralizing  with  chalk, 
filtering,  concentrating,  precipitating  with  alcohol;  (3)  by  the  action 
of  diastase  (infusion  of  malt)  upon  hydrated  starch.  As  soon  as 
the  starch  is  dissolved  the  liquid  must  be  rapidly  heated  to  boiling 
to  prevent  saccharification. 

Commercial  dextrin  is  a  colorless,  or  yellowish,  amorphous  pow- 
der, soluble  in  H20  in  all  proportions,  forming  mucilaginous  liquids. 
When  obtained  by  evaporation  of  its  solution,  it  forms  masse  re- 
sembling gum  arabic  in  appearance.  Its  solutions  are  dextrogyrous, 
and  reduce  cupro-potassic  solutions  under  the  influence  of  heat,  to 
amounts  varying  with  the  method  of  formation  of  the  sample.  It  is 
colored  wine-red  by  iodine.  It  is  extensively  used  as  a  substitute  for 
gum  acacia. 

By  the  action  of  diastase  upon  starch,  four  dextrins  are  produced : 
(1)  Erythrodextrin,  which  is  colored  red  by  iodine,  and  which  is 
easily  attacked  by  diastase;  (2)  Achroodextrin  «,  not  colored  by 
iodine;  partially  converted  into  sugar  by  diastase;  rotary  power 


CARBOHYDRATES  247 

[a]  D=4-210°;  reducing  power  (glucose=ilOO)=:12 ;  (3)  Achroo- 
dextrin  /?,  not  colored  by  iodine,  nor  decomposable  in  twenty-four 
hours  by  diastase;  rotary  power-f-190° ;  reducing  power=12;  (4) 
Achroodextrin  y ,  not  colored  by  iodine,  nor  decomposed  by  diastase; 
slowly  converted  into  glucose  by  dilute  H2S04;  rotary  powers 
+150°;  reducing  power=28. 

An  explanation  of  this  series  of  transformations  has  been  sug- 
gested in  the  supposition  that  the  molecule  of  starch  consists  of 
50(C12H20010)  ;  that  this  is  first  converted  into  soluble  starch 
10(C12H20010)  ;  and  that  this  is  then  converted  into  the  different 
forms  of  dextrin  by  a  series  of  hydrations  attended  by  simultaneous 
formation  of  maltose,  of  which  the  final  result  might  be  represented 
by  the  equation : 

10(C12H20010)    +  8(H20)    =  2(C12H20010)    +  8(C1:E220U) 
Soluble    starch.  Water.  Achroodextrin.  Maltose. 

Cellulose — Cellulin — Lignin — forms  the  basis  of  all  vegetable 
tissues.  It  exists,  almost  pure,  in  the  pith  of  elder  and  of  other 
plants,  in  the  purer,  unsized  papers,  in  cotton,  and  in  the  silky 
appendages  of  certain  seeds.  Cotton,  freed  from  extraneous  matter 
by  boiling  with  KOH  and  afterwards  with  dilute  HC1,  yields  pure 
cellulose  (absorbent  cotton).  It  is  white,  has  the  shape  of  the  fiber 
from  which  it  was  derived,  is  insoluble  in  the  usual  solvents,  but 
soluble  in  the  dark  blue  liquid  formed  by  dissolving  copper  in 
ammonia  in  contact  with  air. 

Vegetable  parchment — Parchment  paper — is  obtained  by  dip- 
ping unsized  paper  for  an  instant  in  H2S04,  diluted  with  an  equal 
volume  of  H2O,  washing  thoroughly,  and  drying.  It  is  a  tough  ma- 
terial resembling  animal  parchment. 

Gun-cotton — Pyroxylin — Nitrocellulose — is  obtained  by  dipping 
pure  cotton  in  a  cold  mixture  of  one  part  of  HN03  and  two-thirds  of 
H2S04  for  from  three  to  ten  minutes,  washing  thoroughly,  and  dry- 
ing. It  consists  of  hexanitrocellulose,  C12H14(O.N02)604,  is  violently 
explosive,  and  is  insoluble  in  a  mixture  of  alcohol  and  ether. 

Soluble  pyroxylin — is  obtained  by  acting  on  cotton  with  a  warm 
mixture  of  twenty  parts  of  nitre  and  thirty  parts  of  concentrated 
H2S04,  washing  and  drying.  It  consists  of  penta-  and  tetra-nitro- 
cellulose,  is  soluble  in  a  mixture  of  alcohol  and  ether,  and  is  used  in 
the  preparation  of  collodion.  Explosive  gelatin,  or  smokeless  pow- 
der, is  a  desiccated  mixture  of  nitro-glycerol  and  collodion.  Celluloid 
is  a  mixture  of  gun-cotton  and  camphor,  combined  by  pressure. 

Tests  for  Carbohydrates. — A.  Furfurole  Reaction — T aliens'  Re- 
action for  pentoses  (not  hexoses)  depends  upon  the  fact  that 
these  compounds  yield  furfurole  by  loss  of  water  when  they  are 
heated  with  HC1.  The  reagent  consists  of  1  gm.  phloroglucin,  dis- 
solved in  500  cc.  of  30  per  cent.  HC1,  to  which  30  drops  of  a  30  per 


248  TEXT-BOOK   OF    CHEMISTRY 

cent,  solution  of  FeCl3  are  added.  About  5  cc.  of  the  reagent  are 
heated  to  boiling,  and  the  liquid  added.  The  formation  of  a  cherry- 
red  color  indicates  the  presence  of  a  pentose.  Orcin  may  be  substi- 
tuted for  phloroglucin  in  the  reagent,  when  the  color  produced  is 
green.  Orcin  has  the  advantage  over  phloroglucin  that  the  glucuron- 
ates  do  not  react  with  the  former,  but  do  with  the  latter. 

B.  Aldehyde  and  Ketone  Reactions. — These  reactions  depend 
upon  the  presence  in  the  carbohydrates  of  the  CHO  or  CO  group,  and 
are  consequently  given  by  cane-sugar,  non-reducing  dextrins  and 
starch,  which  do  not  contain  such  groups,  only  after  their  hydrolysis 
by  boiling  with  dilute  acids;  but  are  given  by  other  substances  con- 
taining ketone  or  aldehyde  groups. 

1.  Copper  Reduction  Tests. — These  and  other  reduction  tests  are 
produced  not  only  by  aldoses  and  ketoses,  but  also  by  other  reducing 
agents.  Therefore,  such  substances,  as  well  as  albumin,  must  be 
excluded  before  these  tests  are  resorted  to.  This  may  be  accomplished 
by  Focke's  method,  by  boiling  10  cc.  of  liquid  (urine)  with  5  cc.  of 
CuS04  solution  (1:10),  filtering,  adding  2  cc.  Na2C03  solution  (1:10) 
to  the  cool  filtrate,  and  filtering  again  after  standing. 

Trommer's  Reaction  is  the  earliest  form  of  reduction  test  for 
sugar.  It  consists  in  adding  about  one-eighth  of  NaOH  or  KOH  solu- 
tion (1:10)  to  the  dilute  saccharine  liquid,  then  two  to  three  drops 
of  CuS04  solution  (1 :10)  and  heating  the  blue  liquid  just  to  boiling. 
A  yellow  ppt.  is  formed,  which  becomes  darker  and  reddish  on 
boiling. 

Feeling's  Test. — The  reagent  must  be  kept  in  two  solutions,  which 
are  to  be  mixed  immediately  before  use.  If  the  reagent  is  made  in  a 
single  solution  it  is  prone  to  self-reduction.  Solution  I  consists  of 
34.653  gms.  of  crystallized  CuS04,  dissolved  in  water  to  500  cc. ;  and 
II,  of  130  gms.  of  Rochelle  salt  dissolved  to  500  cc.  in  NaOH  solution 
of  sp.  gr.  1.12.  When  required  for  use  equal  volumes  of  the  two 
solutions  are  mixed,  and  the  mixture  diluted  with  four  volumes  of 
water.  A  few  cc.  of  this  liquid  are  heated  to  boiling,  and  the  saccha- 
rine liquid  (urine)  added  in  small  portions,  the  contents  of  the  test- 
tube  being  heated  short  of  boiling,  but  not  boiled,  after  each  addition. 
A  reducing  sugar  produces  a  yellow  or  red  ppt.,  which  forms  more  or 
less  rapidly  according  to  the  amount  of  sugar  present.  The  liquid 
should  not  be  boiled  after  addition  of  urine,  as  creatinine  and  uric 
acid  may  reduce  by  boiling.  Glucuronates  and  glycosurates  also 
reduce.  There  are  many  modifications  of  this  test,  in  which  potassium 
tartrate,  mannite,  glycerol,  etc.,  are  used  in  place  of  Rochelle  salt, 
but  they  present  no  advantages  over  the  above.  Pavy's  solution  is  a 
modified  Fehling,  containing  a  notable  amount  of  ammonia.  It  has 
the  advantage  for  quantitative  work  that  the  blue  color  is  more 
sharply  discharged  on  total  reduction,  but  it  is  open  to  the  objection 
that  the  ppt.  is  soluble  in  the  ammoniacal  liquid. 


CARBOHYDRATES  249 

2.  Bismuth  Reduction   Tests. — Boettger's   test   may  be  applied 
either  in  the  manner  originally  indicated,  or  in  Nylander's  or  Almen's 
modifications.     Equal  portions  of  the  liquid  are  placed  in  two  test 
tubes,  to  each  of  which  enough  solution  of  Na2C03  is  added  to  make 
the  reaction  distinctly  alkaline,  and  to  one  a  little  powdered  bismuth 
subnitrate,  and  to  the  other  a  little  powdered  litharge  are  added. 
The  contents  of  the  two  tubes  are  then  heated  to  boiling,  when,  if  the 
bismuth  powder  becomes  black  and  the  litharge  remains  unchanged, 
the  presence  of  a  reducing  sugar  may  be  inferred.     The  purpose  of 
the  litharge  is  to  guard  against  error  from  the  presence  of  sulphur 
compounds,    which   blacken    both    the    bismuth    and   lead   powders. 
Nylander's  solution  is  made  by  adding  4  gms.  of  Rochelle  salts,  2  gms. 
of  bismuth  subnitrate  and  10  gms.  of  caustic  soda  to  90  cc.  of  water, 
boiling,  cooling  and  filtering.    To  use  the  test  1  cc.  of  the  reagent  is 
added  to  the  liquid  and  the  mixture  boiled,  when  a  reducing  sugar 
causes  the  formation  of  a  gray  or  black  ppt.    A  parallel  testing  with 
litharge  is  also  required.     An   affirmative   result  is  obtained  with 
urine  in  the  absence  of  sugar  when  large  doses  of  quinine  have  been 
taken,  but  uric  acid  and  creatinine  do  not  react,  and  therefore  this 
reaction  is  preferable  to  the  copper  reduction  tests,  although  glucuro- 
nates  react  with  it. 

3.  Osazone  Reaction. — The  phenylhydrazine  test,  or  Fischer's,  or 
Riegler's  test  depends  upon  the  formation  of  osazones  by  all  mono- 
saccharides  and  disaccharides  containing  CO  or  CHO  groups.     To 
10  cc.  of  the  liquid  (urine)   in  a  test  tube,  add  0.5  gm.  phenylhy- 
drazine hydrochloride  and  1  gm.  sodium  acetate,  and  cause  the  pow- 
ders to  dissolve  by  warming,  and,  if  necessary,  the  addition  of  water, 
and  leave  the  test  tube  in  a  boiling-water  bath  for  one  hour,  after 
which  cool  it  by  immersion  in  cold  water.     If  a  ketose  or  aldose, 
whether  hexose  or  pentose,  or  a  glucuronate  is  present  a  yellow  ppt. 
is  formed,  usually  crystalline,  which  should  be  collected  and  examined 
microscopically.    Needle-shaped  crystals  are  formed  by  glucose,  fruc- 
tose, maltose  and  glucuronic  acid.    The  osazones  of  glucose  and  fruc- 
tose are  one  and  the  same  substance.    The  several  osazones  have  dif- 
ferent fusing  points:  that  of  glucuronic  acid,  114°-115°;  of  isomal- 
tose,  150°-153°;  of  arabinose,  159°;  of  galactose,  193°;  of  glucose 
and  fructose,  204°-205°,  and  of  maltose,  206°.     To  determine  the 
fusing  point  the  ppt.  is  collected,  dissolved  in  hot  alcohol,  the  solu- 
tion filtered  and  evaporated,  the  crystals  dried  over  H2S04,  placed  in 
a  small  closed  tube  attached  to  the  bulb  of  a  thermometer  by  a  pasted 
slip  of  paper,  and  heated  in  a  paraffin  bath,  the  temperature  being 
noted  when  the  material  fuses.     Aldehydes  and  ketones  also  form 
hydrazones. 

4.  Fermentation    Test. — Three    Smith's    fermentation-tubes    are 
used,  one  (A)   completely  filled  with  water,  one  (B)   with  a  dilute 
solution  of  glucose,  and  the  third  (C)  with  the  liquid  (urine)  to  be 


250  TEXT-BOOK   OF   CHEMISTRY 

tested,  and  each  containing  a  little  compressed  yeast.  The  three 
tubes  are  put  in  warm  place  and  left  over-night,  when  if  gas  has 
collected  in  B  and  C  and  none  in  A  the  urine  contains  sugar ;  if  gas 
has  collected  in  B,  but  none  in  A  or  C  it  is  absent ;  under  any  other 
circumstances  the  yeast  is  at  fault.  The  only  substances  other  than 
glucose  which  respond  to  this  test  are  the  other  fermentable  carbo- 
hydrates, lactose,  maltose  and  fructose. 

CARBOXYLIC  ACIDS. 

These  compounds  are  the  third  products  of  oxidation  of  the  CH3 
groups  of  the  paraffins  and  contain  the  characterizing  group  of  atoms 
0:C.OH  (carboxyl).  They  are  either  pure  acids,  containing  only 
the  carboxyl  and  hydrocarbon  groups;  or  alcohol-acids,  containing 
also  the  groups  CH2OH,  CHOH  or  COH ;  or  aldehyde-acids,  contain- 
ing CHO ;  or  ketone-acids,  containing  CO ;  or  of  still  more  complex 
function,  containing  two  or  more  of  the  above  groups. 

The  most  important  of  the  pure  acids  are  those  of  the  acetic 
(CnH2n02),  and  oxalic  (CnH2w-204)  series,  the  former  of  which  are 
monobasic,  the  latter  dibasic.  Other  pure  acids  of  higher  basicity  are 
also  known  in  which  the  carboxyl  groups  are  substituted  for  hydro- 
gen atoms  in  the  hydrocarbon. 

PARAFFIN     MONOCARBOXYLIC     ACIDS— VOLATILE     FATTY     ACIDS- 
ACETIC  SERIES—SERIES  CnH2nO2 

The  lowest  terms  of  the  series  are  volatile  liquids,  the  highest  are 
solids  and  exist  in  their  glycerol  esters  in  the  fats ;  hence  the  name  of 
volatile  fatty  acids.  The  solid  acids,  the  tenth  and  higher  of  the 
series,  cannot  be  distilled  without  decomposition  except  in  super- 
heated steam. 

As  the  hydrocarbons  may  be  considered  as  the  hydrides  of  the 
alkyls,  and  the  alcohols  as  their  hydroxides,  so  the  acids  may  be 
considered  as  the  hydroxides  of  the  acidyls:  the  acid  or  oxidized 
radicals.  Thus  acetic  acid  is  acetyl  hydroxide,  (CH3.CO)OH. 

These  acids  may  be  obtained: 

(1)  By  oxidation  of  the  corresponding  alcohol  or  aldehyde: 

C2H5.CH2OH+02=C2H5.COOH+H20,  or 
2CH3.CHO+02=2CH3.COOH 

(2)  By  decomposition  of  the  dicarboxylic  acids,  with  elimination 
of  carbon  dioxide: 

COOH.COOH=:H.COOH+CO,,  and 
COOH.CH2.COOH=rCH3.COOH-fCOi; 

(3)  By  the  action  of  carbon  monoxide  upon  an  alkaline  hydroxide 
or  alcoholate: 


CARBOXYLIC   ACIDS  251 

CO+NaOH=H.COONa,   and 
CO+C2H5.O.Na=C2H5.COONa 

(4)  From  the  nitriles,   or  hydrocyanic  esters,  by  the  action  of 
acids  or  alkalies  in  the  presence  of  water: 

HCN+H,0+KOH=H.COOK+NH3,  or 
CH3.CN+2H20+HC1=CH3.COOH+NH4C1 

This  constitutes  a  general  method  for  the  introduction  of  carboxyl, 
starting  from  the  haloid  derivatives  of  the  hydrocarbon.  This  is 
converted  into  the  cyanide,  or  nitrile  by  heating  with  alcoholic  po- 
tassium cyanide: 

BrCH,.CH3+KCN=CNCH2.CH3-f-KBr,  or 
BrCH2.CH2Br+2KCN=CN.CH2.CH2.CN+2KBr 

and  the  cyanide  is  then  converted  into  the  acid  by  elimination 
of  the  nitrogen  as  ammonia,  and  the  substitution  of  OOH  in  its  place 
by  the  action  of  acids  or  of  alkalies: 

CN.CH2.CH3+HC1+2H20=COOH.CH2CH3+NH4C1,  or 
CN.CH2.CH2.CN+2KOH+2H20=COOK.CH2.CH2.COOK+2NH3 

(5)  By   passing   carbon    dioxide    through    ethereal   solutions   of 
alkyl  magnesium  bromides  or  iodides  and  hydrolyzing  the  product: 

CH3.Mg.Br+C02=CH3.COO.Mg.Br,  and 
CH3.COO.Mg.Br+H20=CH3.COOH+HO.Mg.Br. 

Methan  Acid— Formic  Acid— H.COOH.— Although  it  is  the  first 
term  of  this  series,  formic  acid  differs  from  its  superior  homologues 
in  several  respects:  (1)  It  is  not  a  pure  acid,  but  an  aldehyde-acid, 
the  single  carbon  atom  forming  part  of  both  groups:  0:C<^^; 

(2)  The  halogens  do  not  convert  it  into  halide-formic  (or  carbonic) 
acids,  but  split  it  to  carbon  dioxide  and  the  hydracid : 

H.COOH+C12=C02+2HC1 

(3)  By  elimination  of  water  it  yields  carbon  monoxide: 

H.COOH=CO+H20 

(4)  It  produces  no  acidyl  halide  or  anhydride  corresponding  to 
those  of  its  superior  homologues. 

It  occurs  in  the  bodies  of  ants  and  of  other  insects,  and  in  the 
blood,  bile,  perspiration  and  muscular  fluid  of  mammalia.  It  is  pro- 
duced by  oxidation  of  sugar,  starch,  gelatin,  albumin,  etc.;  in  the 
fermentation  of  diabetic  urine;  by  the  action  of  potash  upon  chloro- 
form: 

CHC13+4KOH=H.COOK+3KC1+2H20 

By  the  action  of  hydrating  agents  upon  its  nitrile,  hydrocyanic 
acid: 

HCN+2H20=:H.COO(NH4) 


252  TEXT-BOOK   OF    CHEMISTRY 

And  by  decomposition  of  oxalic  acid  in  the  presence  of  glycerol 
at  about  100°: 

COOH.COOH=H.COOH+C02 

It  is  a  colorless  liquid  of  acid  taste  and  penetrating  odor,  b.  p. 
100°,  crystallizes  at  0°,  miscible  with  water.  It  is  decomposed  by 
mineral  acids  to  carbon  monoxide  and  water :  H.COOH:=CO-hH20 ; 
by  oxidizing  agents  to  carbon  dioxide  and  water:  2H.COOH-f-02= 
2H20+2C02;  and  by  caustic  alkalies  to  a  carbonate  and  hydrogen; 
H.COOH+KOH=KHC03+H2.  It  reduces  the  salts  of  Au,  Ag, 
and  Hg. 

Orthoformic  Acid,  CH(OH)3,  so  called  because  of  its  analogy  to 
tribasic  or  "ortho"  phosphoric  acid  OP(OH)3  is  only  known  in  its 
esters  (p.  277). 

Ethan  Acid— Acetic  Acid — Acetyl  Hydroxide — Acidum  aceticum 
(U.  S.  P.)—  CH3.COOH— is  formed  by  the  general  methods,  and  (1) 
by  the  action  of  carbon  dioxide  on  sodium  methyl:  C02-f-NaCH3= 
CHg.COONa;  and  (2)  by  the  oxidation  of  many  organic  substances: 
starch,  sugar,  gelatin,  fibrin,  cellulose,  tartaric  and  citric  acids,  etc. 
Commercially  it  is  obtained  as  acetic  acid  and  as  vinegar.  As  the 
former  it  is  produced  by  the  dry  distillation  of  wood,  in  which  four 
products  are  obtained:  charcoal,  remaining  in  the  retort,  an  illumi- 
nating gas,  a  tarry  liquid,  wood-tar,  and  an  acid  liquid,  ' '  crude  wood 
vinegar "  or  "pyroxylic  spirit."  The  last  is  a  highly  complex  liquid, 
containing  acids  of  this  series,  methyl  acetate,  and  cyclic  compounds. 
It  is  redistilled  fractionally,  the  first  portions  being  used  as  a  source 
of  methylic  alcohol,  and  the  later  portions  of  acetic  acid.  In  these 
the  acid  is  converted  into  sodium  acetate,  which,  after  calcination,  is 
decomposed  by  H2S04,  and  the  liberated  acetic  acid  distilled  off. 
The  product  so  obtained,  the  commercial  acid,  contains  36  per  cent, 
of  true  acetic  acid,  sp.  gr.  1.047. 

Vinegar  is  obtained  by  the  indirect  atmospheric  oxidation  of 
various  alcoholic  liquids,  containing  less  than  10  per  cent,  of  ethyl 
alcohol,  under  the  influence  of  the  growth  of  a  true  ferment,  Bac- 
terium aceti,  or  ' '  mother  of  vinegar, ' '  with  free  access  of  air.  It  con- 
tains from  5  to  10  per  cent,  of  acetic  acid. 

Pure  acetic  acid,  called  glacial  acetic  acid  (acidum  aceticum 
glaciale,  U.  S.  P.),  is  obtained  by  distilling  dry  sodium  acetate  with 
a  slight  excess  of  H2S04.  It  is  a  colorless  liquid,  b.  p.  119°,  crystal- 
lizes to  an  ice-mass  at  17°,  sp.  gr.  1.0497  at  20°,  having  an  acid  taste 
and  the  odor  of  vinegar,  and  causing  vesication  when  applied  to  the 
skin.  Glacial  acetic  acid  on  dilution  with  water  contracts  until  the 
sp.  gr.  becomes  1.0754  with  a  dilution  of  77  per  cent,  of  acid,  cor- 
responding to  a  hydrate :  CH3COOH-)-H20,  and  on  further  dilution 
the  sp.  gr.  diminishes  until  at  50  per  cent,  it  is  the  same  as  that  of 
the  glacial  acid.  Acetic  acid  is  a  good  solvent  for  many  organic  sub- 


CARBOXYLIC   ACIDS  253 

stances',  and  is  itself  soluble  in  water  and  in  alcohol  in  all  proportions. 

Vapor  of  acetic  acid  burns  with  a  pale-blue  flame  and  is  decom- 
posed at  a  red  heat.  Glacial  acetic  acid  only  decomposes  calcium  car- 
bonate in  the  presence  of  water.  Hot  H2S04  blackens  and  decom- 
poses it,  S02  and  C02  being  given  off.  Solutions  of  potassium  acetate, 
when  electrolyzed,  yield  ethane,  C2He.  Under  ordinary  circumstances 
chlorine  acts  upon  acetic  acid  slowly,  more  actively  under  the  influ- 
ence of  sunlight,  to  form  the  three  products  of  substitution  men- 
tioned below. 

Acetates  are  soluble  in  water,  except  basic  ferric  acetate.  Potas- 
sium acetate,  heated  with  arsenic  trioxide  forms  cacodyl  oxide.  Cal- 
cium acetate,  when  heated  alone,  yields  acetone;  and  with  calcium 
formate,  aldehyde. 

Monochloracetic  acid  is  a  solid,  f.' p.  62°,  b.  p.  186°,  obtained, 
along  with  acetyl  chloride,  by  the  action  of  chlorine  upon  acetic 
anhydride : 

(CH3.CO)20+C12=CH2C1.COOH+CH3.COC1 

Dichloracetic  acid  is  a  colorless  liquid,  b.  p.  190°,  obtained  by 
heating  chloral  with  aqueous  potassium  cyanide: 

CC13.CHO+H20+KCN=CHC12.COOH+KC1+HCN 

Trichloracetic  acid  is  an  odorless,  strongly  vesicant,  crystalline 
solid,  f.  p.  46°,  b.  p.  195°,  obtained  by  oxidation  of  chloral  hydrate 
by  nitric  acid: 

2CC13.CH(OH)2+02=2CC13.COOH+2H20 

Propan  Acid — Propionic  Acid — Methylacetic  acid — CH3.CH2.- 
COOH — is  formed  by  the  action  of  caustic  potash  upon  sugar,  starch 
and  gum;  during  acetic  fermentation;  in  the  distillation  of  wood; 
during  the  putrefaction  of  peas,  beans,  etc. ;  by  the  oxidation  of  nor- 
mal propylic  alcohol,  etc.  It  is  best  prepared  by  heating  ethyl 
cyanide  with  potash  until  the  odor  of  the  ester  has  disappeared;  the 
acid  'is  then  liberated  from  its  potassium  compound  by  H2S04  and 
purified. 

It  is  a  colorless  liquid,  sp.  gr.  0.996,  b.  p.  140°,  solidifies  at 
— 36.5°,  odor  and  taste  like  those  of  acetic  acid,  mixes  with  water 
and  alcohol.  Its  salts  are  crystalline  and  soluble. 

Butan  Acid— Butyric  Acid— Ethylacetic  Acid— CH3.CH,.CH2.- 
COOH — exists  in  milk,  perspiration,  muscle,  spleen,  contents  of 
stomach  and  large  intestine,  feces,  and  guano ;  in  butter,  particularly 
when  rancid;  in  certain  fruits  and  in  yeast.  It  is  formed  by  the 
action  of  H2S04  and  manganese  dioxide,  aided  by  heat,  upon  cheese, 
starch,  gelatin,  etc.;  during  the  combustion  of  tobacco  (as  ammonium 
butyrate)  ;  by  the  action  of  HN03  upon  oleic  acid  during  the 
decomposition  of  many  animal  and  vegetable  substances,  and  par- 
ticularly by  butyric  fermentation  of  carbohydrates  in  presence  of 


254  TEXT-BOOK   OF   CHEMISTRY 

proteins.  This  fermentation  occurs  in  two  stages:  First  the 
glucose  is  converted  into  lactic  acid:  C6H-1206=2C8HeOs ;  and 
this  in  turn  is  decomposed  into  butyric  acid,  carbon  dioxide,  and 
hydrogen :  2C3H(!03=C4H802+2C02+2H2. 

Butyric  acid  is  a  colorless,  mobile  liquid,  having  a  disagreeable, 
persistent  odor  of  rancid  butter,  and  a  sharp,  acid  taste;  soluble  in 
water,  alcohol,  ether,  and  methyl  alcohol;  boils  at  164°,  distilling 
unchanged ;  solidifies  in  a  mixture  of  solid  carbon  dioxide  and  ether ; 
sp.  gr.  0.974  at  15°;  a  good  solvent  of  fats.  It  is  not  acted  on  by 
cold  H2S04  or  HN03.  Hot  HN03  oxidizes  it  to  succinic  acid: 

2CH3.CH2.CH2.COOH+302=2COOH;CH2.CH2.COOH+2H20 

Dry  Cl  in  sunlight,  and  Br  under  heat  and  pressure  form  several 
products  of  substitution.  The  butyrates  are  soluble  in  water. 

Butyric  acid  is  formed  in  the  intestine,  by  the  process  of  fermen- 
tation mentioned  above,  at  the  expense  of  those  portions  of  the  car- 
bohydrate elements  of  food  which  escape  absorption,  and  is  dis- 
charged with  the  feces  as  ammonium  butyrate. 

Isobutyric    Acid— Dimethylacetic    acid— £§3^>  CH.COOH— boils 

at  155°,  has  been  found  in  human  feces.  It  corresponds  to  isobutyl 
alcohol,  from  which  it  is  produced  by  oxidation. 

Pentan  Acids — Valerianic  Acids — Valeric  Acids — C4H9.COOH— 
102. — Corresponding  to  the  four  primary  amylic  alcohols,  there  are 
four  possible  amylic  or  valerianic  acids : 

Normal  Valerianic  Acid — Valeric  Acid — Propyl-acetic  acid — 
is  obtained  by  the  oxidation  of  normal  amylic  alcohol.  It  is  an  oily 
liquid,  boils  at  185°,  and  has  an  odor  resembling  that  of  butyric  acid. 

Ordinary  Valerianic  Acid — Valeric  Acid — Isopropyl-acetic  acid 
— Isovaleric  acid — This  acid  exists  in  the  oil  of  the  porpoise,  and  in 
valerian  root  and  in  angelica  root.  It  is  formed  during  putrid  fer- 
mentation or  oxidation  of  proteins.  It  occurs  in  the  urine  and  feces 
in  typhoid,  variola,  and  acute  atrophy  of  the  liver.  It  is  also  formed 
in  a  variety  of  chemical  reactions,  and  notably  by  the  oxidation  of 
amylic  alcohol. 

The  ordinary  valerianic  acid  is  an  oily,  colorless  liquid,  having  an 
odor  of  old  cheese,  and  a  sharp,  acrid  taste.  It  solidifies  at  — 51  ° ; 
boils  at  173°-175°;  sp.  gr.  0.9343-0.9465  at  20°;  burns  with  a  white. 
smoky  flame.  It  dissolves  in  30  parts  of  water,  and  in  alcohol  ;m<l 
ether  in  all  proportions.  It  dissolves  phosphorus,  camphor  and  cer- 
tain resins. 

Hexan  Acids— Caproic  Acids — Hexylic  acids — C5H,,.COOH — 116.— Tlicro 
exist  seven  isomeres  having  the  composition  indicated  above,  some  of  which 
•have  been  prepared  from  butter,  cocoa-oil  and  cheese,  and  by  decomposition  of 
amyl  cyanide,  or  by  oxidation  of  hexyl  alcohol. 

The  acid  obtained  from  butter,  in  which  it  exists  as  a  glyceric  ester,  is  a 
colorless,  oily  liquid,  boils  at  205° ;  sp.  gr.  0.931  at  15°,  has  an  odor  of  perspira- 


CARBOXYLIC    ACIDS  255 

tion  arid  a  sharp,  acid  taste;   is  very  sparingly  soluble  in  water,  but  soluble  in 
alcohol.     It  is  the  normal  hexylic  acid:  CH3. (CH2)4.COOH. 

"Caprylic  Acid — Octylic  acid — C7H15.COOH — 144 — accompanies  caproic  acid 
in  butter,  cocoa-oil,  etc.  It  is  a  solid;  fuses  at  15°;  boils  at  236°;  almost 
insoluble  in  H2O. 

Capric  Acid — Decylic  acid—  C9H19.COOH— 172 — exists  in  butter,  cocoa-oil, 
etc.,  associated  with  caproic  and  caprylic  acids  in  their  glyceric  esters,  and  in 
the  residues  of  distillation  of  Scotch  whisky,  as  amyl  caprate.  It  is  a  white, 
crystalline  solid;  melts  at  27.5°;  boils  at  273°. 

Laurie  Acid — Laurostearic  acid — CnHag.COOH — 200 — is  a  solid,  fusible  at 
43.5°;  obtained  from  laurel  berries,  cocoa-butter  and  other  vegetable  fats. 

Myristic  Acid— C13H27.COOH— 228.— A  crystalline  solid,  fusible  at  54°; 
existing  in  many  vegetable  oils,  cow's  butter  and  spermaceti. 

Palmitic  Acid — C15H31.COOH — 256 — exists  in  palm-oil,  in  com- 
bination when  the  oil  is  fresh,  and  free  when  the  oil  is  old;  it  also 
enters  into  the  composition  of  nearly  all  animal  and  vegetable  fats. 
It  is  obtained  from  the  fats,  palm-oil,  etc.,  by  saponification  with 
caustic  potas,h  and  subsequent  decomposition  of  the  soap  by  a  strong 
acid.  It  is  formed  by  the  action  of  caustic  potash  in  fusion  upon 
cetyl  alcohol  (ethal),  and  by  the  action  of  the  same  reagent  upon 
oleic  acid. 

Palmitic  acid  is  a  white,  crystalline  solid;  odorless,  tasteless; 
lighter  than  H20,  in  which  it  is  insoluble;  quite  soluble  in  alcohol 
and  in  ether ;  fuses  at  62  ° ;  distils  unchanged  with  vapor  of  water. 

Margaric  Acid — C]nH33.COOH — 270 — formerly  supposed  to  exist  as  a 
glyceride  in  all  fats,  solid  and  liquid.  What  had  been  taken  for  margaric  acid 
was  a  mixture  of  90  per  cent,  of  palmitic  and  10  per  cent,  of  stearic  acid. 
It  is  obtained  by  the  action  of  potassium  hydroxide  upon  cetyl  cyanide,  as  a 
white,  crystalline  body;  fusible  at  59.9°. 

Stearic  Acid — C17H35.COOH — 284 — exists  as  a  glyceride  in  all 
solid  fats  and  in  many  oils,  and  also  free  to  a  limited  extent. 

To  obtain  it  pure  the  fat  is  saponified  with  an  alkali,  and  the  soap 
decomposed  by  HC1 ;  the  mixture  of  fatty  acids  is  dissolved  in  a  large 
quantity  of  alcohol,  and  the  boiling  solution  partly  precipitated  by 
the  addition  of  concentrated  solution  of  barium  acetate.  The  pre- 
cipitate is  collected,  washed  and  decomposed  by  HC1;  the  stearic 
acid  which  separates  is  washed  and  recrystallized  from  alcohol.  The 
process  is  repeated  until  the  product  fuses  at  70°.  Stearic  acid  is 
formed  from  oleic  acid  by  the  action  of  iodine  under  pressure  at 
270°-280°. 

Pure  stearic  acid  is  a  colorless,  odorless,  tasteless  solid;  fusible  at 
70°;  unctuous  to  the  touch;  insoluble  in  H20,  very  soluble  in  alcohol 
and  in  ether.  The  alkaline  stearates  are  soluble  in  H20 ;  those  of 
Ca,  Ba,  and  Pb  are  insoluble. 

Stearic  and  palmitic  acids  exist  free  in  the  intestine  during 
the  digestion  of  fats,  a  portion  of  which  is  decomposed  by  the  action 


256  TEXT-BOOK   OF   CHEMISTRY 

of  the  pancreatic  secretion  into  fatty  acids  and  glycerol.     The  same 
decomposition  also  occurs  in  the  presence  of  putrefying  proteins. 

Arachic  Acid  —  C^H^-COOK  —  312  —  exists  as  a  glyceride  in  peanut  oil  (now 
largely  used  as  a  substitute  for  olive  oil  )  ,  in  oil  of  ben,  and  in  small  quantity 
in  butter.  It  is  a  crystalline  solid,  which  melts  at  75°. 

PARAFFIN  DICARBOXYLIC  ACIDS—  OXALIC  SERIES—  CnH2M  _204 

These  acids  are  derivable  from  the  paraffins  by  oxidation  of  two 
CH3  groups,  or  from  the  diprimary  alcohols  by  oxidation  of  the 
CH2OH  groups.  They  contain  two  carboxyl  groups  and  are  there- 
fore dibasic.  But  one  acid  is  possibly  derivable  from  ethane  (oxalic 
acid),  and  from  propane  (malonic  acid).  From  the  two  butanes 
two  acids  are  derivable;  from  the  three  pentanes  four  acids,  and 
from  the  five  hexanes  nine  acids;  all  of  which  are  known.  The 
molecular  structure  of  the  acids  derivable  from  the  butanes  and 
pentanes  is  shown  in  the  following  formulae: 

CH3\ 

CH3.CH2.CH2.CH8  CH,—  CH 

CH3/ 

Butane.  Isobutane. 

COOH\ 
COOH.CH2.CHa.COOH  COOH—  CH 

CH3/ 
Succinic   acid.  Isosuccinlc  acid. 

CH8.CH2.CH2.CH2.CH3  (CH3)2:CH.CH2.CH3  (CH3)4::C 

Normal    Pentane.  Dimethyl-ethyl  Methane.     Tetramethyl   Methane. 

COOH.  (  CH2  )  3.COOH  (  COOH  )  2  :  CH.CH2.CH8  (  COOH  )  2  :  C  :  (  CH3  )  , 

Glutaric   Acid.  Ethyl-malonic  Acid.  Dimetbyl-malonic  Acid. 


Methyl-succinic  Acid. 

As  the  monocarboxylic  acids  may  be  considered  as  the  hydroxides 
of  the  acidyls  (p.  250),  corresponding  to  the  alkyls  of  the  monohydric 
alcohols  (p.  211),  so  the  dicarboxylic  acids  are  the  hydroxides  of  bi- 
valent acid  radicals,  which  we  will  call  acidylenes,  corresponding  to 
the  alkylenes  of  the  dihydric  alcohols  (p.  221). 

The  acids  of  this  series  may  be  obtained:  (1)  By  the  oxidation  of 
the  corresponding  diprimary  alcohols,  dialdehydes,  primary  oxyalde- 
hydes,  primary  oxyacids,  aldehyde  acids,  paraffin  monocarboxylic 
acids,  olefine  monocarboxylic  acids  or  paraffins. 

(2)  By  the  reduction  of  the  olefine  dicarboxylic  acids. 

(3)  By  the  action  of  silver  upon  the  monoiodo  or  monobromo 
fatty  acids: 

2BrCH2.COOH+2Ag=2AgBr+COOH.CH2.CH2.COOH 


CARBOXYLIC   ACIDS  257 

(4)  By  the  action  of  acids  or  alkalies  upon  the  cyano  fatty  acids  : 

CN.CH2.COOH+2H20=NH3+COOH.CH2.COOH 
or  upon  the  dicyanides  : 
CN.CH2.CH2.CN+4H20=2NH3+COOH.CH2.CH2COOH.     (p.  251)  . 

The  action  of  heat  upon  these  acids  and  their  salts  differs  accord- 
ing to  the  attachment  of  the  carboxyl  groups.  (1)  Oxalic  acid  and 
acids  in  which  the  two  carboxyls  are  attached  to  the  same  carbon 
atom  are  either  decomposed  into  the  two  oxides  of  carbon  and  water  : 

COOH.COOH=C02+CO+H20 

or  into  carbon  dioxide  and  a  fatty  acid  : 

COOH.COOH=C02+H.COOH 

This  splitting  off  of  C02  occurs  more  readily  with  other  acids 
than  with  the  monocarboxylic  acids  (p.  251),  and  may  be  utilized  in 
the  same  manner  to  pass  to  compounds  of  less  carbon  content.  Thus 
from  malonic  acid  to  acetic  acid,  to  monochloracetic  acid,  to  glycollic 
acid  and  to  oxalic  acid  : 

COOH.CH9.COOH—  C02=CH3.COOH—  ->CH2.C1.COOH—  > 
CH2.OH.COOH—  >  COOH.COOH 

(2)  When  the  two  carboxyls  are  attached  to  neighboring  carbon 
atoms   the    acids    are    decomposed    into    water    and    an    anhydride 
(p.  269)  : 

C^TT    f^O\ 

COOH.CH2.CH2.COOH^:H20+  I  '         0 

CH2.CO/ 

(3)  When  the  carboxyls  are   attached  to  remote  carbon  atoms 
their  calcium  salts  are  converted  by  heat  into  cyclic  ketones  and 
carbonate  : 

/CH.2CH2.C02\  n  ,  /CH2.CH2\ 

— 


Oxalic  Acid—  COOH.COOH—  90—  C2H204,  2Aq—  126—  does  not 
occur  free  in  nature,  but  in  the  oxalates  of  K,  Na,  Ca,  Mg,  and  Fe  in 
the  juices  of  many  plants  :  sorrel,  rhubarb,  cinchona,  oak,  etc.  ;  as  a 
native  ferrous  oxalate  ;  and  in  small  quantity  in  human  urine.  It  is 
prepared  artificially  by  oxidizing  sugar  or  starch  by  HN03,  or  by  the 
action  of  an  alkaline  hydroxide  in  fusion  upon  sawdust.  The  soluble 
alkaline  oxalate  obtained  by  the  latter  method  is  converted  into  the 
insoluble  Ca  or  Pb  salt,  which  is  washed  and  decomposed  by  an 
equivalent  quantity  of  H2S04  or  H2S  ;  and  the  liberated  acid  purified 
by  recrystallization. 

Oxalic  acid  is  also  formed  by  the  oxidation  of  many  organic 
substances:  alcohol,  glycol,  sugar,  etc.  ;-by  the  action  of  potash  in 
fusion  upon  the  alkaline  formates;  and  by  the  action  of  K  or  Na 
upon  C02. 


258  TEXT-BOOK   OF    CHEMISTRY 

It  crystallizes  in  transparent  prisms,  containing  2  Aq,  which 
effloresce  on  exposure  to  air,  and  lose  their  Aq  slowly  but  completely 
at  100°,  or  in  a  dry  vacuum.  It  fuses  at  98°  in  its  Aq;  at  110-132° 
it  sublimes  in  the  anhydrous  form,  while  a  portion  is  decomposed; 
above  160°  the  decomposition  is  more  extensive;  H20,  C02,  CO,  and 
formic  acid  are  produced,  while  a  portion  of  the  acid  is  sublimed  un- 
changed. It  dissolves  in  15.5  parts  of  water  at  10°;  the  presence  of 
HNO3  increases  its  solubility.  It  is  quite  soluble  in  alcohol.  It  has 
a  sharp  taste  and  an  acid  reaction  in  solution. 

Oxalic  acid  is  readily  oxidized;  in  watery  solution  it  is  converted 
into  CO2  and  H20,  slowly  by  simple  exposure  to  air,  more  rapidly  in 
the  presence  of  platinum-black  or  of  the  salts  of  platinum  and  gold, 
under  the  influence  of  sunlight,  or  when  heated  with  HN03,  man- 
ganese dioxide,  chromic  acid,  Br,  Cl,  or  hypochlorous  acid.  Its  oxi- 
dation, when  it  is  triturated  dry  with  lead  dioxide,  is  sufficiently 
active  to  heat  the  mass  to  redness.  H2S04,  H3P04  and  other  dehy- 
drating agents  decompose  it  into  H20,  CO  and  C02. 

Analytical  Characters. —  (1)  In  neutral  or  alkaline  solution:  a 
white  ppt.  with  a  solution  of  Ca  salt.  (2)  Silver  nitrate:  a  white 
ppt,  soluble  in  HN03,  and  in  NH4OH.  The  ppt.  does  not  darken 
when  the  fluid  is  boiled,  but  when  dried  and  heated  on  platinum  foil, 
it  explodes.  (3)  Lead  acetate,  in  solutions  not  too  dilute:  a  white 
ppt.,  soluble  in  HN03,  insoluble  in  acetic  acid. 

Toxicology. — Although  certain  oxalates  are  constant  constituents  of  vege- 
table food  and  of  the  human  body,  the  acid  itself,  as  well  as  monopotassic 
oxalate,  is  a  violent  poison  when  taken  internally,  acting  both  locally  as  a 
corrosive  upon  the  tissues  with  which  it  comes  in  contact  and  as  a  true  poison, 
the  predominance  of  either  action  depending  upon  the  concentration  of  the 
solution.  Dilute  solutions  may  produce  death  without  pain  or  vomiting,  and 
after  symptoms  resembling  those  of  narcotic  poisoning.  Death  has  followed  a 
dose  of  4  gm.  of  the  solid  acid,  and  recovery  a  dose  of  30  gm.  in  solution. 
When  death  occurs,  it  may  be  almost  instantaneously,  usually  within  half  an 
hour;  sometimes  after  weeks  or  months,  from  secondary  causes. 

The  treatment,  which  must  be  as  expeditious  as  possible,  consists  in  the 
administration,  first,  of  lime  or  magnesia,  or  a  soluble  salt  of  Ca  or  Mg,  sus- 
pended or  dissolved  in  a  small  quantity  of  H20  or  mucilaginous  fluid;  after- 
ward, if  vomiting  has  not  occurred  spontaneously,  and  if  the  symptoms  of 
corrosion  have  not  been  severe,  an  emetic  may  be  given.  The  alkaline  car- 
bonates are  of  no  value  in  cases  of  oxalic-acid  poisoning,  as  the  oxalates  which 
they  form  are  soluble  and  almost  as  poisonous  as  the  acid  itself.  The  in- 
gestion  of  water,  or  the  administration  of  warm  water  as  an  emetic,  is  contra- 
indicated  \\hen  the  poison  has  been  taken  in  the  solid  form  (or  where  doubt 
exists  as  to  what  form  it  was  taken  in),  as  they  dissolve,  and  thus  favor  the 
absorption  of  the  poison. 

Malonic  Acid—  CH2\COOH~ is  a  Product  of  the  oxidation  of  malic  acid 
or  of  normal  propyl  glycol.  II  is  best  obtained  by  Hie  general  method  ». 
|i.  -2~>7.  Monochloracetic  acid  is  converted  into  cyano-acetic  acid  by  heating  in 
alkaline  solution  with  K(  N  : 

(II  ,C1.COOH+KCN=CN.CH2.COOH+KC1 


ALCOHOL-ACIDS — OXYACIDS  259 

Thevcyano-acid  is  then  hydrolyzed  by  heating  with  KOH  or  HC1,  thus: 
CN.CH2.COOH-f2H20=COOH.CH8.COOH+NH8 

It  forms  large  prismatic  crystals,  soluble  in  water,  alcohol  and  ether; 
fusible  at  132°,  and  decomposed  at  about  150°  into  acetic  acid  and  carbon 
dioxide. 

CH2— COOH 

Succinic  Acid —  — 118 — exists  in  amber,  coal,  fossil  wood,  and 

CH2— COOH 

in  small  quantity  in  animal  and  vegetable  tissues.  Its  presence  has  been  de- 
tected in  the  normal  urine  after  the  use  of  fruits  and  of  asparagus,  in  the 
parenchymatous  fluids  of  the  spleen,  thyroid,  and  thymus,  and  in  the  fluids  of 
hydrocele  and  of  hydatid  cysts.  It  is  also  formed  in  small  quantity  during 
alcoholic  fermentation;  as  a  product  of  oxidation  of  many  fats  and  fatty  acids; 
and  by  synthesis  from  ethylene  cyanide: 

CN.  ( CH2 )  2.CN-f4H20=COOH.  ( CH2 )  2.COOH-f-2NH3 

It  may  also  be  obtained  by  dry  distillation  of  amber,  or  by  the  fermentation 
of  malic  acid. 

It  crystallizes  in  large  prisms  or  hexagonal  plates,  which  are  colorless, 
odorless,  permanent  in  air,  acid  in  taste,  soluble  in  water,  sparingly  so  in 
ether  and  in  cold  alcohol.  It  fuses  at  180°,  and  distils  with  partial  decom- 
position at  235°.  It  withstands  the  action  of  oxidizing  agents.  Reducing 
agents  convert  it  into  the  corresponding  acid  of  the  fatty  series,  butyric  acid. 
With  Br  it  forms  products  of  substitution.  H2SO4  is  without  action  upon  it. 
Phosphoric  anhydrides  remove  H2O  and  convert  it  into  succinic  anhydride, 
C4H403. 

Glutaric  Acid — COOH.  ( CH2 )  3.COOH— Normal  Pyrotartaric  acid — the  next 
superior  homologue  of  succinic  acid,  is  formed  by  reduction  of  a  oxyglutaric 
acid  (p.  263).  It  crystallizes  in  large  plates,  very  soluble  in  water,  which 
fuse  at  27°.  The  corresponding  amido-acid  is  one  of  the  products  of  decomposi- 
tion of  protein  bodies. 

ALCOHOL-ACIDS— OXYACIDS. 

These    acids   contain,   besides   the   carboxyl   group,    one   of   the 

groups  CH2OH,  CHOH,  or  COH,  which  characterize  the  primary, 

secondary,  and  tertiary  alcohols.    They,  therefore,  have  the  function 

of  alcohols,  primary,  secondary,  or  tertiary,  as  well  as  that  of  acids : 

CH2OH  CH8  (CH3)2 

COOH  CHOH  COH 

COOH  COOH 

Gly collie    acid  aOxypropionic    acid  a  Oxyisobutyric  acid 

(primary).  (secondary).  (tertiary). 

They  may  be  considered  as  derived  either  from  the  di-  and  poly- 
atomic alcohols  (glycols,  glycerols,  etc.)  by  incomplete  oxidation,  as 
COOH.CH2OH  from  CH2OH.CH2OH ;  or  from  the  pure  acids  by  sub- 
stitution of  OH  for  H  atoms  in  the  remaining  hydrocarbon  groups, 
as  CH2OH.CH2.CHU.COOH;  CH2OH.CHOH.CH9.COOH,  and  CH2- 
OH.CHOH.CHOH.COOH  from  CH3.CH2.CH2.COOH. 

The  basicity  of  these  acids  is  represented  by  the  number  of  car- 
boxyl groups  which  they  contain,  their  atomicity  by  the  number  of 
hydroxyls.  Thus  CH2OH.CHOH.COOH  is  monobasic  and  triatomic. 


260  TEXT-BOOK   OF   CHEMISTRY 

The  algebraic  formulae  of  the  several  monobasic  series  are 
CnH2nOs;  CnH2n04,  CnH2nOs,  etc.,  those  of  the  dibasic  series 
CnH2W-205,  CnH2f»-206,  etc.  ;  and  those  of  the  tribasic  series  CnEbn-iO, 
C«H2n-40s,  etc. 

OXYACETIC  SERIES.     CnH2n08 

The  acids  of  this  series  contain  one  carboxyl  and  one  alcoholic 
group.  They  are,  therefore,  monobasic  and  diatomic,  and  may  be 
considered  as  derived  from  the  glycols  by  oxidation  of  one  CH2OH 
group,  or  from  the  acids  of  the  acetic  series  by  substitution  of  OH  for 
H  in  a  hydrocarbon  group  (oxyacetic). 

They  are  formed:  (1)  By  the  limited  oxidation  of  the  correspond- 
ing glycols  or  oxyaldehydes  : 

CH2OH.CH2OH+02=CH2OH.COOH+H20,  or 
2CH2OH.CHO+02=2CH2OH.COOH 

(2)  By  the  action  of  nascent  hydrogen  upon  the  aldehyde  or 
ketone  acids,  or  upon  the  acids  of  the  oxalic  series: 

CHO.COOH+H,=CH2OH.COOH,  or 
CH3.CO.COOH+H2=CH3.CHOH.COOH,  or 
COOH.COOH+2H2=CH2OH.COOH+H2O 

(3)  By  heating  the  monohalogen  fatty  acids  with  silver  or  po- 
tassium hydroxides,  or  with  water: 

CH2C1.COOH+KHO=CH2OH.COOH+KC1,  or 
CH2C1.COOH+H20=HC1+CH2OH.COOH 

(4)  From  the  aldehydes  and  ketones,  by  their  conversion,  first 
into  oxycyanides  by  the  action  of  hydrocyanic  acid: 

CH3.CHO+HCN=CH3.CH  /°g 
and  the  action  upon  these  of  acids  or  alkalies: 

CH3.CH  /*  +2H20=CH3.CHOH.COOH+NH3 


Isomeres  —  Position  or  Place  Isomery.  —  Considering  the  oxybutyric  acids 
as  derived  from  normal  and  isobutyric  acids  by  substitution  of  one  OH  for  a 
hydrogen  atom  in  a  hydrocarbon  group,  the  following  five  derivatives  are  possible: 


I. 

II. 

III. 

IV. 

V. 

CH, 

CH, 

CH, 

CH2OH 

H,C     CH, 

H,C     CH2OH 

H,C     CH, 

CH2 

CH3 

CHOH 

CH2 

\/ 
CH 

\/ 
CH 

\/ 
COH 

CH2 

CHOH 

CHa 

CH2 

COOH 

COOH 

COOH 

COOH 

COOH 

COOH 

COOH 

Alpha 

Beta 

(Jamma 

Beta 

Alpha 

Normal 

o\y 

oxy 

ONV- 

Isobutyric 

Oxyisobutyric 

Oxyisobutyric 

I'.utyrir 
acid. 

butyric 
acid. 

butyric 

acid. 

butvrle 
acid. 

acid. 

ucid. 

acid. 

ALCOHOL-ACIDS  —  OXYACIDS  261 

Whi\e  III,  IV,  and  V  are  obviously  different  in  molecular  structure  from 
each  other  and  from  I  and  II,  in  that  the  latter  contain  the  group  CHOH, 
while^the  former  contain  the  groups  CH,OH,CH,  and  COH,  the  only  difference 
between  I  and  II,  whose  molecules  are  composed  of  identical  groups,  is  in  the 
position  or  place  of  the  alcoholic  hydroxyl  with  reference  to  the  carboxyl  group. 
Place  isomeres  of  this  kind  are  distinguished  by  designating  that  in  which 
the  second  substituted  group  (in  this  case  the  OH)  is  attached  to  the  carbon 
atom  contiguous  to  the  first  as  the  alpha,  or  1  -compound,  and  the  others  by 
the  succeeding  Greek  letters,  or  by  the  numerals  in  the  order  of  the  removal 
of  the  position  of  the  second  substitution.  Thus  II  above  is  Beta  oxybutyric 
or  2-oxybutyric  acid.  (See  Orientation,  p.  337.) 

The  a,  /3,  y-^  and  6  acids  differ  in  their  products  of  dehydration:  The  « 
acids  yield  cyclic  double  esters,  called  lactids,  by  elimination  of  H20  from 
two  molecules  of  the  acid.  The  /3  acids  are  converted  into  unsaturated  acids 
by  loss  of  H2O  from  one  molecule  of  the  acid: 

CH2OH.CH2.COOH=CH2  :  CH.COOH-f-H2O. 

The  y  and  6  acids  and  those  of  greater  carbon  content,  are  converted  into 
simple  cyclic  esters,  called  lactones,  by  elimination  of  H2O  from  a  single 
molecule  of  the  acid. 

By  further  oxidation  the  primary  oxyacids  containing  CH2OH  yield  alde- 
hyde acids: 


and  then  dibasic  acids: 

2CHO.COOH-f  02=2COOH.COOH  ; 

The  secondary  acids,  containing  CHOH,  yield  ketone  acids: 
2CH3.CHOH.COOH+02=2CH3.CO.COOH+2H20, 

And  the  tertiary  acids,  containing  COH,  yield  ketones,  carbon  dioxide  and 
water  : 

2  cg3^)  COH.COOH-f-02=2CH8.CO.CH3-f  2C02-j-2H2O. 

The  hydrogen  of  their  carboxyl  group  may  be  replaced  to  form  salts,  esters, 
or  amides;  and  the  hydroxyl  of  their  alcoholic  group  may  be  replaced  by  alkali 
metals,  alkyls,  or  acidyls.  In  other  words,  they  behave  as  acids  and  as  alcohols. 

Oxy  formic  Acid  —  Carbonic  acid  —  OC(OH)2.  —  Although,  this 
acid  does  not  exist  free,  but  is  decomposed  as  soon  as  liberated  into 
C02  and  H20,  its  salts,  the  carbonates,  are  well  known  and  quite 
stable.  The  position  of  this  acid  in  this  series  is  an  apparent 
anomaly,  as  it  is  dibasic,  not  monobasic  like  the  other  terms  of  the 
series.  But  if  we  bear  in  mind  that  the  basic  nature  of  the  H  atom 
in  a  hydroxyl  depends  upon  its  close  union  with  a  CO  group  (or  some 
other  electro-negative  group),  it  is  evident  that  the  two  H  atoms  in 
the  inferior  homologue  of  glycollic  acid,  being  similarly  united  to  the 
same  CO  group,  must  be  equally  basic  : 

CH2OH  /OH 

|  —    CH2    =     OC 

COOH  \OH 

Glycollic  acid,  Carbonic  acid. 

Indeed,  carbonic  acid  is  not  an  alcohol  acid,  but  a  pure  acid,  as  it 
contains  no  alcoholic  group. 


262  TEXT-BOOK   OF    CHEMISTRY 

Esters  are  also  known  corresponding  to  orthocarbonic  acid: 
C(OH)4  although  the  acid  itself  is  unknown. 

Glycollic  Acid— Oxyacetic  acid— CH2OH.COOH— is  formed  by 
the  oxidation  of  glycol,  by  the  action  of  nitrous  acid  upon  glycocoll, 
and  by  the  action  of  KOH  upon  monochloracetic  acid,  or  upon 
glyoxal,  CHO.CHO. 

It  forms  deliquescent  acicular  crystals,  very  soluble  in  water,  alco- 
hol and  ether.  It  fuses  at  80  °.  It  is  oxidized  by  HN03  to  oxalic  acid. 

Lactic  Acids — Oxypropionic  acids — Alpha  oxypropionic  acid— 
Efhidene  lactic  acid— CH3.CHOH.COOH— is  formed  from  milk 
sugar,  cane  sugar,  gum  and  starch  by  lactic  fermentation,  induced 
by  the  lactic  acid  bacillus.  It  consequently  exists  Ifc  many  soured 
products,  such  as  soured  milk,  sour-krout,  fermented  beet-juice,  and 
the  waste  liquors  of  starch  works  and  of  tanneries.  It  is  formed  in 
the  stomach  during  digestion  of  carbohydrates.  It  is  prepared  by 
allowing  a  mixture  of  cane  sugar,  tartaric  acid,  rotten  cheese,  skim 
milk  and  chalk  to  ferment  for  ten  days  at  35°.  It  has  also  been 
obtained  by  oxidation  of  alpha  propylene  glycol: 

CH3.CHOH.CH2OH+02=CH3.CHOH.COOH+H20 

Lactic  acid  of  fermentation  is  a  colorless,  or  yellowish,  syrupy 
liquid;  sp.  gr.  1.215  at  20°;  soluble  in  water,  alcohol  and  ether.  It 
does  not  distil  without  decomposition,  but  when  heated  it  yields 
lactid,  carbon  monoxide,  aldehyde  and  water.  Heated  to  130°  with 
dilute  sulphuric  acid  it  splits  into  aldehyde  and  formic  acid: 

CH3CHOH.COOH=CH3.CHO+H.COOH 

Oxidizing  agents  convert  it  into  pyroracemic  acid:  CH3.CO.- 
COOH,  or,  if  more  energetic,  split  it  up  into  acetic  acid  and  carbon 
dioxide : 

CH3.CHOH.COOH+02=CH3.COOH+C02+H20 

Hydriodic  acid  reduces  it  to  propionic  acid ;  but  hydrobromic  acid 
converts  it  into  <*-bromopropionic  acid. 

Ethidene  lactic  acid  contains  an  asymmetric  carbon  atom  (p.  239)  : 
CH3.C*HOH.COOH;  and  that  produced  by  lactic  fermentation  is 
optically  inactive  (d+1).  The  dextro  acid,  also  known  as  sarcolactic 
or  paralactic  acid,  is  best  obtained  from  Liebig's  meat  extract;  and 
is  also  produced  by  allowing  Penicillium  glaucum  to  grow  in  a  solu- 
tion of  inactive  ammonium  lactate.  It  exists  in  muscular  tissue  after 
death  yand  during  contraction,  and  in  the  spleen,  lymphatic  glands, 
thymus,  thyroid,  blood,  bile,  transudates,  in  the  perspiration  in  puer- 
peral fever,  and  in  the  urine  after  violent  exercise,  in  yellow  atrophy 
of  the  liver  and  in  phosphorus  poisoning,  either  free  or  in  com- 
bination. The  acid  in  muscular  tissue  probably  originates  from 
glycogen. 


ALCOHOL-ACIDS — OXYACIDS  263 

Laevolactic  Acid  is  formed  by  the  growth  of  Bacillus  acidi  Ice- 
volactici  in  a  solution  of  cane  sugar. 

Ethylene  Lactic  Acid — Beta  oxypropionic  acid — Hydracrylic 
acid— CH2OH.CH2.COOH— the  third  form  of  lactic  acid,  is  formed 
by  the  action  of  moist  silver  oxide  upon  /?-iodo-  or  /?-chloropropionic 
acid ;  by  the  saponification  of  ethylene  cyanhydrine ;  or  by  the  oxida- 
tion of  the  corresponding  glycol.  It  is  a  thick,  uncrystallizable 
syrup,  which  is  converted  by  dehydration  into  acrylic  acid: 

CH2OH.CH2.COOH=CH2  :CH.COOH+H20. 
On  oxidation  it  yields  oxalic  acid  and  carbon  dioxide : 
2(CH2OH.CH2.COOH)+502=2(COOH.COOH)+2C02+4H20 

Oxybutyric  Acids.— Five  isomeres  are  possible  (p.  260).  Beta  oxybutyric 
acid— CH3.C*HOH.CH2.COOH,  is  formed  by  the  action  of  sodium  amalgam 
upon  acetoacetic  ester:  CH3.CO.CH2.COOH-f  H2=CH3.CHOH.CH2.COOH.  The 
Isevo-acid,  a  colorless  syrup,  readily  soluble  in  water,  alcohol  and  ether,  occurs, 
accompanied  by  acetoacetic  acid,  in  the  blood  and  urine  in  severe  cases  of 
diabetes. 

MONOXYDICARBOXYLIC  SERIES— CnH2n_  2O5. 

The  acids  of  this  series  contain  two  carboxyls  and  one  alcoholic  group. 
They  are,  therefore,  dibasic  and  triatomic,  and  may  be  considered  as  derived 
from  the  glycerols  by  oxidation  of  both  CH2OH  groups.  They  may  also  be 
considered  as  derived  from  the  paraffin  dicarboxylic  acids  (oxalic  series),  above 
the  first,  by  substitution  of  OH  for  H  in  a  hydrocarbon  group,  in  the  same 
manner  as  the  acids  of  the  oxyacetic  series  are  derived  from  those  of  the 
acetic  series. 

Tartronic  Acid— Oxymalonic  acid— COOH.CHOH.COOH— is  formed  by 
the  action  of  moist  silver  oxide  upon  monochloro-  or  monobromo-malonic  acid, 
or  by  oxidation  of  glycerol  by  potassium  permanganate.  It  crystallizes  in  large 
prisms,  readily  soluble  in  water,  alcohol,  and  ether,  and  fusible  at  184°. 

Malic  Acid— Oxysuccinic  acid— COOH.CH2.C*HOH.COOH— exists  in  three 
modifications.  The  laevo-acid  exists  free,  and  in  combination  with  K,  Na,  Ca, 
Mg,  and  organic  bases  in  apples,  pears,  and  similar  fruits,  and  in  the  berries 
of  the  mountain  ash  and  in  gooseberries.  The  inactive  (d-(-l)  acid  may  be 
obtained  from  monobromo-succinic  acid  by  the  action  either  of  moist  silver 
oxide,  of  dilute  HC1,  of  dilute  NaOH,  or  even  of  boiling  water;  and  by  several 
other  methods.  The  dextro-acid  is  obtained  by  the  reduction  of  dextro-tartaric 
acid  by  hydriodic  acid. 

The  natural  malic  acid  crystallizes  in  prismatic  needles;  odorless;  acid  in 
taste;  fusible  at  100°;  deliquescent;  very  soluble  in  water  and  in  alcohol. 
Heated  to  140°  it  loses  water  with  formation  of  fumaric  acid,  COOH.CH  rCH.COOH. 

CH.CO\ 
At    180°    it    yields    water,    fumaric    acid    and    maleic    anhydride,     ||  O. 

CH.CO/ 

Reducing  agents   convert   it   into   succinic   acid.     The  malates   are   oxidized   to 
carbonates  in  the  body. 

Oxyglutaric  Acid  exists  in  the  two  isomeres:  a  oxyglutaric  acid,  COOH.- 
CH(OH).CH2.CH2.COOH,  which  occurs  in  molasses,  crystallizes  with  difficulty, 
and  fuses  at  72°;  and  /?  oxyglutaric  acid,  COOH.CH2CHOH.CH2.COOH,  which 
fuses  at  95°. 


264  TEXT-BOOK   OF   CHEMISTRY 

DIOXYDICARBOXYLIC  ACIDS— CnH2n_A- 

Tartaric  Acids— Dioxyethylene  Succinic  Acids.— COOH.CHOH.- 
CHOH.COOH  (and  see  p.  160)— There  exist  four  acids  having  the 
composition  C4H606,  which  are  readily  convertible  one  into  the  other. 
They  are:  Dextro-tartaric,  or  ordinary  tartaric  acid;  Icevo-tartaric 
acid;  mesotartaric,  or  antitartaric  acid;  and  racemic,  or  paratartaric 
acid.  The  first  three  of  these  are  stereoisomeres,  due  to  the  presence  of 
two  asymmetric  carbon  atoms  in  the  molecule,  whose  molecular  struc- 
ture has  been  discussed  under  the  head  of  space  isomery  (p.  239). 
Mesotartaric  acid,  which  is  optically  inactive,  has  a  molecular  struc- 
ture differing  from  those  of  the  d-  and  1-  acids,  into  which  it  cannot 
be  split.  Racemic  acid,  also  optically  inactive,  is  the  (d-J-l)  acid, 
and  can  be  readily  decomposed  into  them  or  separated  from  a  mix- 
ture of  them. 

Dextro-tartaric  Acid — Ordinary  tartaric  acid — Acidum  tartaricum 
(U.  S.  P.) — occurs,  both  free  and  in  combination,  in  the  sap  of  the 
vine  and  in  many  other  vegetable  juices  and  fruits,  particularly  in 
grape-juice.  Although  this  is  probably  the  only  tartaric  acid  existing 
in  nature,  all  four  varieties  may  occur  in  the  commercial  acid,  being 
formed  during  the  process  of  manufacture.  Tartaric  acid  is  obtained 
in  the  arts  from  hydropotassic  tartrate,  or  cream  of  tartar. 

The  ordinary  tartaric  acid  crystallizes  in  large  prisms ;  very  solu- 
ble in  H20  and  in  alcohol;  acid  in  taste  and  reaction.  Heated  with 
water  at  165°-175°  it  is  converted  into  mesotartaric  and  racemic 
acids.  It  fuses  at  170°;  at  180°  it  loses  H20,  and  is  gradually  con- 
verted into  an  anhydride;  at  200° -210°  it  is  decomposed  with  forma- 
tion of  pyruvic  acid,  C3H/)3,  and  pyrotartaric  acid,  C5H804;  at 
higher  temperatures  C02,  CO,  H20,  hydrocarbons  and  charcoal  are 
produced. 

Tartaric  acid  is  attacked  by  oxidizing  agents  with  formation  of 
C02,  H20,  and,  in  some  instances,  formic  and  oxalic  acids.  Certain 
reducing  agents  convert  it  into  malic  and  succinic  acids.  With  fum- 
ing HN03  it  forms  a  dinitro-compound,  which  is  very  unstable,  and 
which,  when  decomposed  below  36°,  yields  tartaric  acid.  It  forms 
a  precipitate  with  lime-water,  soluble  in  an  excess  of  H20.  In 
not  too  dilute  solution  it  forms  a  precipitate  with  potassium  sulphate 
solution.  It  does  not  precipitate  with  the  salts  of  Ca.  When  heated 
with  a  solution  of  auric  chloride  it  precipitates  the  gold  in  the 
metallic  form. 

When  taken  into  the  economy,  as  it  frequently  is  in  the  form  of 
tartrates,  the  greater  part  is  oxidized  to  carbonic  acid  (carbonates)  ; 
but,  if  taken  in  sufficient  quantity,  a  portion  is  excreted  unchanged 
in  the  urine  and  perspiration.  The  free  acid  is  poisonous  in  large 
doses.  The  acids  and  its  salts  are  largely  used  in  pharmacy  and  in 
dyeing.  (See  p.  160.) 


ALDEHYDE-ACIDS  265 

Lcevb-tartaric  —  forms  crystals  similar  to  those  of  the  dextro  acid, 
but  having  opposite  hemihedral  facets,  so  that  the  crystals  of  one 
acid  "resemble  the  reflection  of  those  of  the  other  in  a  mirror. 

Racemic  Acid  —  (d+l)  Tartaric  acid  —  is  produced  when  concen- 
trated solutions  of  equal  quantities  of  d-  and  1-tartaric  acids  are 
mixed.  It  is  formed  by  oxidation  of  dulcitol  and  of  mannitol.  It  is 
obtained  by  the  action  of  moist  silver  oxide  upon  dibromo  succinic 
acid: 

COOH.CHBr.CHBr.COOH+2AgOH=COOH.CHOH.- 
CHOH.COOH+2AgBr; 

and  by  several  other  synthetic  methods.  It  crystallizes  in  rhom- 
bic prisms,  less  soluble  in  water  than  ordinary  tartaric  acid,  and 
fuses  at  205°. 

Mesotartaric  Acid  —  Inactive  Tartaric  acid  —  is  obtained  by  oxida- 
tion of  erythrol  ;  or  by  heating  dextrotartaric  acid  with  water  at  165  ° 
for  two  days. 

HIGHER  DICARBOXYLIC  OXYACIDS. 

The  carbohydrates,  on  oxidation  with  nitric  acid,  yield  tetroxydicarboxylic 
acids:  COOH.(CHOH)4.COOH.  Among  these  are:  mannosaccharic  acids; 
saccharic  acids;  and  mucic  acid.  Of  the  three  saccharic  acids  the  d-acid  is 
the  best  known.  It  is  produced  by  oxidation  of  many  carbohydrates,  including 
cane  sugar  and  grape  sugar,  by  nitric  acid,  and  by  the  action  of  bromine  water 
on  glucuronic  acid.  Nascent  H  reduces  it  to  glucuronic  acid.  It  forms  a  syrup 
or  a  deliquescent  solid,  which,  on  standing,  changes  to  a  crystalline  lactone. 
Mucic  acid  is  produced  by  the  oxidation  of  dulcitol,  milk  sugar,  and  the  gums. 
It  is  a  white  solid,  almost  insoluble  in  cold  water  and  in  alcohol,  which  fuses 
at  210°. 

OXYTRICARBOXYLIC  ACIDS—  CnH2rt_A. 

/CH2.COOH 
Citric  Acid  —  HO.C—  COOH        ,  exists  in  the  juices  of  many  fruits,  lemon, 

\CH2.COOH 

strawberry,  currant,  and  in  small  quantity,  as  calcium  citrate,  in  cow's  milk. 
It  is  obtained  commercially  from  lemon  juice.  It  crystallizes  in  large,  rhombic 
prisms,  very  soluble  in  water  and  in  alcohol.  It  fuses  at  100°  ;  at  175°  it  is 
decomposed  with  loss  of  water  and  formation  of  aconitic  acid;  and  at  a  higher 
temperature  C02  is  given  off  and  citraconic  and  itaconic  acids  are  produced. 
In  the  body  its  salts  are  oxidized  to  carbonates. 

ALDEHYDE-ACIDS. 

These  are  substances  having  both  aldehyde  and  acid  functions,  and  con- 
taining the  groups  CHO  and  COOH.  The  simplest  of  the  class  is  formic  acid, 
already  referred  to  as  the  first  term  of  the  acetic  series,  in  which,  however,  the 

/TT 
carbon  atom  is  common  to  the  two  groups  :  O  :  C  / 


Glyoxylic   Acid  —  CHO.  COOH  —  when  produced  unites  with  water  to   form 
a  hydrate:    (OH)2:CH.COOH,  corresponding  to  chloral  hydrate:    (OH)2:CH.CC13. 


266  TEXT-BOOK   OF   CHEMISTRY 

This  is  a  thick  syrup,  or  it  forms  rhombic  prisms.  It  is  produced  by  heating 
dichloracetic  acid  with  water  at  230°: 

CHCl2.COOH-j-H2O=CHO.COOH-|-2HCl. 
It  has  the  reducing  power  and  other  properties  of  the  aldehydes. 

KETONE-ACIDS. 

These  compounds  contain  both  the  ketonic  and  carboxyl  groups,  CO  and 
COOH. 

The  monoketone-monocarboxylic  acids  contain  one  CO  and  one  COOH. 
According  as  the  CO  group  occupies  the  position  adjacent  to  the  carboxyl,  or 
further  removed  therefrom,  these  acids  are  designated  as  a,  /3,  y,  etc.;  thus 
CH8.CH2.CO.COOH=a,  CH3.CO.CH2.COOH=/3,  etc. 

The  a,  -y,  6,  etc.,  acids  are  much  more  stable  than  the  /3 -acids,  and  may  be 
obtained  by  oxidation  of  the  corresponding  secondary  alcohol  acids.  The  a 
acids  are  derivable  from  formic  acid  by  substitution  of  acidyls  for  the  extra- 
carboxylic  hydrogen:  (CH3.CO)  .COOH. 

Pyruvic  Acid — Pyroracemic  acid — CH3.CO.COOH — is  formed  by  oxidation  of 
a-oxypropionic  acid: 

2CH8.CHOH.COOH-(-O2:=2CH3.CO.COOH-|-2H.!O. 
It  is  also  formed  by  distillation  of  tartaric  acid: 

COOH.CHOH.CHOH.COOH=CH8.CO.COOH+C024-H20. 

The  /3 -ketone  acids  are  more  unstable,  and  are  decomposed  by  heat  with 
formation  of  ketone  and  carbon  dioxide: 

COOH.CH2.CO.CH3=C02-fCH8.CO.CH8. 

Their  esters  are,  however,  quite  stable,  and  are  employed  in  many  syntheses. 
The  /3  acids  bear  the  same  relation  to  acetic  acid  that  the  a  acids  do  to  formic 
acid :  ~  ( CH8.CO )  ,CH2.COOH. 

Aceto-acetic  Acid — Diacetic  Acid — CH3.CO.CH2.COOH — may  be  obtained 
as  a  thick,  strongly  acid  liquid  by  saponification  of  its  esters.  Heat  decomposes 
it  into  acetone  and  carbon  dioxide,  according  to  the  equation  given  above. 
Aceto-acetic  acid  accompanies  /3  oxybutyric  acid  and  acetone  in  the  urine  in 
diabetes.  (See  Aceto-acetic  ester,  p.  278). 

Mesoxalic  Acid— Dioxymalonic  acid — HO/C\COOH~~is  the  monoketone- 
dicarboxylic  acid,  COOH.CO.COOH,  combined  with  water  in  the  same  manner 
as  chloral  hydrate  and  glyoxylic  acid.  Esters  are  known  corresponding  to  both 
forms:  oxymalonic  esters,  CO:  (COO.C2H5)2,  and  dioxymalonic  esters, 
C(OH)2:(COO.C2HB)2.  Mesoxalic  acid  is  obtained  by  the  action  of  boiling 
barium  hydroxide  upon  dibromomalonic  acid: 

COOH.CBr2.COOH4-Ba  ( OH )  2=COOH.C  ( OH )  2.COOH-f  BaBr2, 

or  upon  alloxan  (mesoxalylurea) .  It  crystallizes  in  prisms,  very  soluble  in 
water,  fusible  at  115°.  On  evaporation  of  its  aqueous  solution  it  decomposes 
into  carbon  monoxide,  water  and  oxalic  acid;  at  higher  temperatures  it  yields 
carbon  dioxide  and  glyoxylic  acid. 

OXYALDEHYDE  AND  OXYKETONE  ACIDS. 

These  acids  contain  alcoholic  groups,  CH2OH,  CHOH,  or  COH  in  addition 
to  carboxyl  and  cither  tin-  aldehyde  or  ketone  group,  CHO  or  CO. 

Glucuronic  Acid— CHO.  (CHOH)  4.COOH— is  a  derivative  of  glucose: 
CHn.  ((  Il<  IH  |4.CH2OH.  It  is  a  syrup  which  passes  into  a  crystalline  lactone 


SIMPLE   ETHERS  267 

on  ivarmihg.  It  occurs  in  the  urine  in  small  quantity  normally,  in  combination 
with  phenol,  skatole  and  indole,  and  with  camphors,  chloral  and  other  sub- 
stance^ when  these  are  present. 

SIMPLE  ETHERS. 

These  substances  have  been  referred  to  (p.  209)  as  the  simplest 
products  of  oxidation  of  the  hydrocarbons.  The  term  ether  was  for- 
merly applied  to  any  substance  produced  by  the  action  of  an  acid 
upon  an  alcohol.  Such  products  belong,  however,  to  two  distinct 
classes  : 

(1)  The  simple  ethers,  or  ethers,  which  are  the  oxides  of  the 
hydrocarbon  radicals,  and  the  counterparts  of  the  metallic  oxides, 
bearing  the  same  relation  to  the  alcohols  that  the  metallic  oxides  do 
to  their  hydroxides: 

CH3.CH2\0  CH3.CH2\0  K\  H\ 

CH3.CH2/U  H/u  K/u 


Ethyl  oxide.  Ethyl  hydroxide.  Potassium  Potassium 

(Ether.)  (Alcohol).  oxide.  hydroxide. 

(2)  The  compound  ethers,  now  called  esters,  which  are  the 
products  of  the  reaction  between  an  acid  and  the  alcohol,  the  latter 
behaving  as  a  basic  hydroxide.  They  are  the  counterparts  of  the 
metallic  salts: 


CH3CH2.0\qo  CH3.CH20\~n  K0\  fin 

HO/&U2  CH3.CH20/bU2  HO/bUa 

Monoethylic  Diethylic  Monopotassic  Dipotassic 

sulphate.  sulphate.  sulphate.  sulphate. 

(Ester-acid.)  (Neutral  ester.)  (Acid  salt.)  (Neutral  salt.) 

Mixed  ethers  differ  from  simple  ethers  in  that  they  contain  differ- 
ent, in  place  of  similar,  alkyls,  as  methyl-ethyl  oxide:  CH3.O.CH2.- 
CH, 

Simple  and  mixed  ethers  are  formed:  (1)  By  interaction  of  the 
alcohols  and  alkyl-sulphuric  acids.  Thus  methyl-sulphuric  acid  and 
ethylic  alcohol  form  methyl-ethyl  oxide: 

S02\OHH'+C2H5.O.H=C2H5.O.CH3+S02:(OH)2 

(2)  By  the  action  of  alkyl  halides  upon  sodium  alcoholates: 

CH3.Cl+C2H5O.Na=NaCl+C2H5.O.CH3 

(3)  By  the  action  of  silver  oxide  upon  alkyl  halides: 

2C2H5I+  Ag20=2AgI+0  (  C2H5)  , 

Methyl  oxide  —  CH3.O.CH3  —  46  —  isomeric  with  ethyl  alcohol,  is 
obtained  by  the  action  of  silver  oxide  upon  methyl  iodide,  or  by  the 
action  of  H2S04  and  boric  acid  upon  methyl  alcohol.  It  is  a  colorless 
gas,  has  an  ethereal  odor,  burns  with  a  pale  flame,  liquefies  at  —  36  ° 
and  boils  at  —  21  °,  is  soluble  in  H20,  H2S04  and  ethylic  alcohol. 


268  TEXT-BOOK   OF   CHEMISTRY 

Ethyl  Oxide— Eihylic  ether— Sulphuric  ether— JEther  (U.  S.  P.) 
— C2H5.O.C,H5. — In  the  manufacture  of  ether  a  mixture  is  made  of 
5  pts.  of  90%  alcohol  and  9  pts.  of  concentrated  H2S04,  in  a  vessel 
surrounded  by  cold  water.  This  mixture  is  introduced  into  a  retort, 
into  which  a  slow  stream  of  alcohol  is  allowed  to  flow  during  the 
remainder  of  the  process.  Heat,  so  regulated  as  not  to  exceed  140°, 
is  then  applied  to  the  retort,  which  is  connected  with  a  well-cooled 
condenser,  and  continued  until  the  temperature  rises  above  the  point 
indicated.  The  distillate  contains  ether,  alcohol,  water  and  dissolved 
gases,  notably  S02.  It  is  shaken  with  water  containing  potash  or 
lime,  and  the  ether  decanted  off.  The  product  is  " washed  ether." 
For  further  purification  it  is  treated  with  calcium  chloride,  or  re- 
cently burnt  lime,  with  which  it  is  left  in  contact  for  24  hours,  and 
from  which  it  is  then  distilled. 

In  the  conversion  of  alcohol  into  ether,  sulphovinic  or  ethyl-sul- 
phuric acid  behaves  as  a  "contact  substance"  and  serves  to  carry  an 
ethyl  radical  from  one  alcohol  molecule  to  another,  with  formation 
of  water  and  regeneration  of  sulphuric  acid.  In  the  first  stage  of 
the  reaction  ethyl-sulphuric  acid  is  formed  by  the  action  of  H2S04 
upon  alcohol,  molecule  for  molecule: 

H2S04+C2H5.OH=H20+C2H5.HS04 

The  ethyl-sulphuric  acid  then  reacts  with  another  molecule  of 
alcohol,  according  to  the  general  reaction  (1)  for  the  formation  of 
ethers,  to  form  ether  and  sulphuric  acid: 

C2H5.HS04+C2H5.OH=H2S04+(C2H5)20 

It  would  seem,  therefore,  that  a  given  quantity  of  H2S04  could 
convert  an  unlimited  amount  of  alcohol  into  ether.  But  the  gradual 
accumulation  of  the.H20  formed  in  the  first  stage  of  the  reaction, 
and  the  occurrence  of  secondary  reactions  in  practice  limit  the  amount 
of  ether  produced  to  about  four  or  five  times  the  bulk  of  acid  used. 

Ether  is  a  colorless  liquid;  has  a  sharp,  burning  taste,  and  a 
peculiar,  tenacious  odor,  characterized  as  ethereal.  Sp.  gr.  0.723  at 
12.5°;  it  boils  at  34.5°.  Its  tension  of  vapor  is  very  great,  especially 
at  high  temperatures ;  and  it  is  exceedingly  volatile.  Water  dissolves 
one-ninth  its  weight  of  ether.  Ethylic  and  methylic  alcohols  are 
miscible  with  it  in  all  proportions.  Ether  is  an  excellent  solvent  of 
many  substances  not  soluble  in  water  and  alcohol.  The  resins  and 
fats  are  readily  soluble  in  ether.  The  salts  of  the  alkaloids  and  many 
vegetable  coloring  matters  are  soluble  in  alcohol  and  water,  but  in- 
soluble in  ether,  while  the  free  alkaloids  are  for  the  most  part  soluble 
in  ether,  but  insoluble,  or  very  sparingly  soluble,  in  water. 

Ether  is  highly  inflammable;  and  burns  with  a  luminous  flame. 
The  vapor  forms  with  air  a  violently  explosive  mixture.  It  is  denser 
than  air,  through  which  it  falls  and  diffuses  itself  to  a  great  dis- 


ACID   ANHYDRIDES  269 

tance ;  caution  is  therefore  required  in  handling  ether  in  a  locality  in 
which  there  is  a  light  or  fire,  especially  if  the  fire  be  near  the  floor. 

Pure  ether  is  neutral  in  reaction.  H2S04  mixes  with  it,  with 
elevation  of  temperature,  and  formation  of  sulphovinic  acid.  With 
sulphuric  anhydride  it  forms  ethyl  sulphate.  HN02,  aided  by  heat, 
oxidizes  it  to  carbon  dioxide  and  acetic  and  oxalic  acids.  Ether, 
saturated  with  HC1  and  distilled,  yields  ethyl  chloride.  Cl,  in  the 
presence  of  H20,  oxidizes  it,  with  formation  of  aldehyde,  acetic  acid, 
and  chloral.  In  the  absence  of  H20,  however,  a  series  of  products  of 
substitution  are  produced,  in  which  2,  4,  and  10  atoms  of  H  are  re- 
placed by  a  corresponding  number  of  atoms  of  Cl.  These  substances 
in  turn,  by  substitution  of  alcoholic  radicals,  or  of  atoms  of  elements, 
for  atoms  of  Cl,  give  rise  to  other  derivatives. 

Ethylene  Oxide — njj  /^ — *s  a  cyclic  ether  corresponding  to  glycol: 
CH2OH.CH2OH=(CH2)2O-f-H2O,  as  ethyl  oxide  corresponds  to  ethylic  alcohol: 

2CH3.CH2.OH=  ( C2H5 )  2O+H2O 

It  is  prepared  by  the  action  of  caustic  potash  on  ethylene  chlorhydrine : 
CH2OH.CH2C1+ KOH=  ( CH2 )  20+KC1+H20 

It  is  a  volatile  liquid,  boils  at  13.5°,  is  neutral  in  reaction  and  mixes  with 
water.  It  unites  with  H2O  to  form  glycol,  and  with  HC1  to  regenerate  ethylene 
chlorhydrine.  Nascent  H  converts  it  into  ethyl  alcohol. 

ACID  ANHYDRIDES. 

The  acid  anhydrides  are  the  oxides  of  the  acid  radicals  (acidyls)  ; 
and  bear  the  same  relation  to  the  acids  that  the  simple  ethers  bear  to 
the  alcohols: 

CH3COOH  CH3.CH2OH 

Acetic    acid.  Ethylic  alcohol. 

CH3.CO\0  CH3.CH2\0 

CH3.CO/U  CH3.CH2/U 

Acetic    anhydride.  Ethylic   ether. 

The  acid  anhydrides  of  the  monobasic  acids  are  produced  by  the 
action  of  the  acidyl  chlorides  upon  anhydrous  salts: 

C2H3O.OK+C2H3O.C1=:(C2H30)20+KC1 

or  by  the  action  of  phosphorus  oxychloride  upon  the  alkali  salts 
of  the  acids.  In  this  method  of  formation  the  acidyl  chloride  is 
first  produced : 

2C2H3O.OK+POC13=2C2H3O.C1+P03K+KC1; 

and  this  acts  upon  an  excess  of  the  salt  according  to  the  above 
equation.  Formic  acid  produces  no  anhydride. 

Acetic  Anhydride — (C2H30)20 — is  a  pungent  liquid  which  boils 


270  TEXT-BOOK   OF    CHEMISTRY 

at  137°.  It  is  formed  by  the  general  methods  and  also  by  heating 
lead  acetate  with  carbon  disulphide  at  165°.  It  serves  for  the  intro- 
duction of  the  radical  acetyl  into  other  molecules. 

ACIDYL  HALIDES. 

These  compounds,  also  known  as  halide  anhydrides,  are  the  halo- 
gen compounds  of  the  acidyls.  They  are  produced:  (1)  By  the  action 
of  the  phosphorus  halides  upon  the  acids  or  their  salts : 

3CH3.COOH+PC13=3CH3.COC1+P03H3 ;  or 

2CH3.COOK+ POC13=2CH3.COC1+P03K+ KC1 ;  or 

CH3.COOH+PC15=CH3.COC1+POC13+HC1 

(2)  By  the  action  of  phosgene  upon  the  acids,  or  their  salts: 

COC12+CH3.COOH=CH3.CO.C1+C02+HC1 

(3)  By  the  action  of  phosphorus  pentoxide  upon  the  acids  in 
presence  of  hydrochloric  acid: 

3CH3.COOH+3HC1+P205=3CH3.CO.C1+2P04H3 ;  or 

(4)  By  the  action  of  chlorine  upon  the  aldehydes: 

C12+CH3.CO.H=CH3.CO.C1+HC1 

Acetyl  Chloride — CH3.CO.C1 — is  a  colorless,  pungent  liquid, 
which  boils  at  55°.  It  is  decomposed  by  water  with  formation  of 
acetic  and  hydrochloric  acids.  With  acetic  acid  it  forms  acetic  an- 
hydride. It  is  used  to  produce  acetyl  derivatives. 

OXIDES  OF  CARBON. 

The  two  oxides  of  carbon  are  also  anhydrides  in  that  they  combine 
with  water  to  produce  acids,  or,  what  amounts  to  the  same  thing, 
with  KOH  to  form  the  K  salts,  thus : 

CO  +  KOH  H.COOK 

Carbon  Potassium  Potassium 

monoxide.  hydroxide.  formate. 

C0a  +  KOH  0:C\QK 

Carbon  Potassium  Monopotassic 

dioxide.  hydroxide.  carbonate. 

Carbon  Monoxide — Carbonous  oxide — Carbonic  oxide — CO — 28 
—is  formed:  (1)  By  burning  C  with  a  limited  supply  of  air. 

(2)  By  passing  dry  carbon  dioxide  over  red-hot  charcoal. 

(3)  By  heating  oxalic  acid  with  sulphuric  acid: 

C204H2=H20+CO+C02 

and  passing  the  gas  through  sodium  hydroxide  to  separate  C02. 

(4)  By  heating  potassium  ferrocyanide  with  H2S04. 


OXIDES  OF  CARBON  271 

It  is  a  colorless,  tasteless  gas:  sp.  gr.  0.9678A;  very  sparingly 
soluble  in  H20  and  in  alcohol.  It  burns  in  air  with  a  blue  flame  to 
C02,  and  it  forms  explosive  mixtures  with  air  and  oxygen.  It  is  a 
valuable  reducing  agent,  and  is  used  for  the  reduction  of  metallic 
oxides  at  a  red  heat.  Ammoniacal  solutions  of  the  cuprous  salts 
absorb  it  readily.  Being  non-saturated,  it  unites  readily  with  0  to 
form  CO2,  and  with  Cl  to  form  COC12,  the  latter  a  colorless,  suffo- 
cating gas,  known  as  phosgene,  or  carbonyl  chloride,  which  is  of 
service  in  the  formation  of  acid  chlorides  and  anhydrides  and  in  a 
variety  of  other  syntheses. 

Toxicology. — Carbon  monoxide  is  an  exceedingly  poisonous  gas,  and  is 
the  chief  toxic  constituent  of  the  gases  given  off  from  blast-furnaces,  from 
defective  flues,  from  open  coal  or  charcoal  fires  and  of  illuminating  gas. 

Poisoning  by  CO  may  occur  in  several  ways.  By  inhalation  of  the  gases 
discharged  from  blast-furnaces  and  from  copper-furnaces,  the  former  contain- 
ing 25  to  32  per  cent,  and  the  latter  13  to  19  per  cent,  of  CO.  By  the  fumes 
given  off  from  charcoal  burned  in  a  confined  space,  which  consists  of  a  mix- 
ture of  the  two  oxides  of  carbon,  the  dioxide  predominating  largely,  especially 
when  the  combustion  is  most  active.  The  following  is  the  composition  of  an 
atmosphere  produced  by  burning  charcoal  in  a  confined  space,  and  which 
proved  rapidly  fatal  to  a  dog:  oxygen,  19.19;  nitrogen,  76.62;  carbon  dioxide, 
4.61;  carbon  monoxide,  0.54;  marsh-gas,  0.04.  Obviously  the  deleterious 
effects  of  charcoal-fumes  are  more  rapidly  fatal  in  proportion  as  the  combus- 
tion is  imperfect  and  the  room  small  and  ill-ventilated. 

A  fruitful  source  of  CO  poisoning,  sometimes  fatal,  but  more  frequently 
producing  languor,  headache  and  debility,  is  to  be  found  in  the  stoves,  furnaces, 
etc.,  used  in  heating  our  dwellings  and  other  buildings,  especially  when  the 
fuel  is  anthracite  coal.  This  fuel  produces  in  its  combustion,  when  the  air 
supply  is  not  abundant,  considerable  quantities  of  CO,  to  which  a  further 
addition  may  be  made  by  the  reduction  of  the  dioxide,  also  formed,  passing 
over  red-hot  iron. 

Fatal  poisoning  by  illuminating  gas  is  of  very  frequent  occurrence.  The 
most  actively  poisonous  ingredient  of  illuminating  gas  is  CO,  which  exists 
in  ordinary  coal-gas  in  the  proportion  of  4  to  7.5  per  cent.,  and  in  water-gas, 
made  by  decomposing  superheated  steam  by  passage  over  red-hot  coke,  and 
subsequent  charging  with  vapor  of  hydrocarbons,  in  the  large  proportion  of 
30-35  per  cent. 

The  method  in  which  CO  produces  its  fatal  effects  is  by  forming  with 
the  blood-coloring  matter  a  compound  which  is  more  stable  than  oxyhemoglobin, 
and  thus  causing  asphyxia  by  destroying  the  power  of  the  blood  corpuscles  of 
carrying  O  from  the  air  to  the  tissues.  This  compound  of  CO  and  hemo- 
globin is  quite  stable,  and  hence  the  symptoms  of  this  form  of  poisoning  are 
very  persistent,  lasting  until  the  place  of  the  coloring-matter  thus  rendered 
useless  is  supplied  by  new  formation.  The  prognosis  is  very  unfavorable  when 
the  amount  of  the  gas  inhaled  has  been  at  all  considerable,  the  treatment 
usually  followed,  i.e.,  artificial  respiration  and  inhalation  of  0,  restoring  the 
altered  coloring  matter  very  slowly.  There  would  seem  to  be  no  form  of 
poisoning  in  which  transfusion  of  blood  is  more  directly  indicated  than  in 
that  by  CO,  but  it  has  been  found  to  be  detrimental  rather  than  beneficial. 

Detection  after  death. — The  blood  of  those  asphyxiated  by  CO  is  per- 
sistently bright-red  in  color.  When  suitably  diluted  and  examined  with  the 
spectroscope,  it  presents  an  absorption  spectrum  (No.  6,  Fig.  19,  p.  273)  of 
two  bands  similar  to  that  of  oxyhi-moglobin  (No.  3,  Fig.  19),  but  in  which 


272  TEXT-BOOK  OF   CHEMISTRY 

the  two  bands  are  more  equal  and  somewhat  nearer  the  violet  end  of  the 
spectrum.  Owing  to  the  greater  stability  of  the  CO  compound,  its  spectrum 
may  be  readily  distinguished  from  that  of  the  O  compound  by  the  addition 
of  a  reducing  agent  (an  ammoniacal  solution  of  ferrous  tartrate),  which 
changes  the  spectrum  of  oxyhemoglobin  to  the  single-band  spectrum  of  hemo- 
globin (No.  1,  Fig.  19),  while  that  of  the  CO  compound  remains  unaltered, 
or  only  fades  partially. 

If  a  solution  of  caustic  soda  of  sp.  gr.  1.3  is  added  to  normal  blood,  a 
black,  slimy  mass  is  formed,  which,  when  spread  upon  a  white  plate,  has  a 
greenish-brown  color.  The  same  reagent  added  to  blood  altered  by  CO  forms 
a  firmly  clotted  mass,  which  in  thin  layers  upon  a  white  surface  is  bright 
red  in  color. 

A  piece  of  gun-cotton  upon  which  platinum-black  has  been  dusted  fires  in 
air  containing  2.5  in  1,000  of  CO. 

Carbon  Dioxide — Carbonic  anhydride — Carbonic  acid  gas — 
C02 — 44 — is  obtained:  (1)  By  burning  C  in  air  or  0.  (2)  By  de- 
composing a  carbonate  (marble=CaCO3)  by  a  mineral  acid  (HC1 
diluted  with  an  equal  volume  of  H20). 

At  ordinary  temperatures  and  pressures  it  is  a  colorless,  suffo- 
cating gas;  has  an  acidulous  taste;  sp.  gr.  1.529  A;  soluble  in  an 
equal  volume  of  H20  at  the  ordinary  pressure,  much  more  soluble  as 
the  pressure  increases.  Soda  water  is  a  solution  of  carbonic  acid  in 
H20  under  increased  pressure.  When  compressed  to  the  extent  of 
38  atmospheres  at  0°;  50  atm.  at  15°;  or  73  atm.  at  30°  it  forms  a 
transparent,  mobile  liquid,  by  whose  evaporation,  when  the  pressure 
is  relieved,  sufficient  cold  is  produced  to  solidify  a  portion  into  a 
snow-like  or  ice-like  mass,  which,  by  spontaneous  evaporation  in  air, 
produces  a  temperature  of  — 90°. 

Carbon  dioxide  neither  burns  nor  does  it  support  combustion. 
When  heated  to  1,300°,  it  is  dissociated  into  CO  and  0.  A  similar 
decomposition  is  brought  about  by  the  passage  through  it  of  electric 
sparks.  When  heated  with  H  it  yields  CO  and  H20.  When  K,  Na, 
or  Mg  is  heated  in  an  atmosphere  of  C02,  the  gas  is  decomposed  with 
formation  of  a  carbonate  and  separation  of  carbon.  When  caused 
to  pass  through  solutions  of  the  hydroxides  of  Na,  K,  Ca,  or  Ba, 
it  is  absorbed,  with  formation  of  the  carbonates  of  those  metals, 
which,  in  the  case  of  the  last  two,  are  deposited  as  white  precipitates. 
Solution  of  potash  is  frequently  used  in  analysis  to  absorb  C02,  and 
lime  and  baryta  water  as  tests  for  its  presence.  The  hydroxides 
mentioned  also  absorb  C02  from  moist  air. 

Atmospheric  Carbon  Dioxide. — Carbon  dioxide  exists  in-  free 
country  air  in  the  proportion  of  about  four  parts  in  10,000.  Its 
sources  are  from:  (1)  Respiration.  Expired  air  contains  about  4.5 
per  cent.  C02.  (2)  Combustion  of  fuel,  illuminating  gas,  etc.  A 
burner  consuming  three  cubic  feet  of  illuminating  gas  per  hour 
produces  as  much  C02  as  is  formed  by  the  respiration  of  seven  human 
beings.  In  a  confined  space  respiration  and  combustion  vitiate  the 


OXIDES  OP  CARBON 


273 


40 


FIG.  19.  Spectra  of:  (1)  Reduced  hemoglobin;  (2)  Oxyhemoglobin,  con- 
centrated; (3)  Same,  dilute;  (4)  Same,  very  dilute;  (5)  Methemoglobin,  in 
faintly  alkaline  solution;  (6)  Carbon  monoxide  hemoglobin;  (7)  Hemochromo- 
gen,  in  alkaline  solution;  (8)  Hematin,  in  acid  solution;  (9)  Hematin,  in  alka- 
line solution;  (10)  Hematoporphyrin,  in  acid  solution. 


274  TEXT-BOOK   OF    CHEMISTRY 

air  in  two  ways:  by  addition  of  carbon  dioxide  and  by  removal  of 
oxygen,  as  the  C02  is  produced  at  the  expense  of  atmospheric  oxygen. 
By  the  other  methods  of  its  origin  it  is  merely  added  to  the  air,  whose 
oxygen-content  remains  nearly  unaltered.  (3)  Fermentation.  For 
every  liter  of  alcohol  produced  384  liters  of  C02  are  added  to  the 
air.  (4)  Tellural  sources,  such  as  volcanic  fissures,  volcanoes,  spring 
waters.  (5)  Manufacturing  operations,  such  as  lime-burning,  cement 
and  brick-making,  iron  furnaces,  etc.  (6)  In  coal  mines  the  after- 
damp contains  a  volume  of  C02  equal  to  that  of  the  fire-damp  ex- 
ploded. 

Notwithstanding  the  large  amounts  of  C02  discharged  into  the 
atmosphere  from  these  several  sources,  and  it  is  estimated  that  the 
amount  is  sufficient  to  double  the  atmospheric  C02-content  in  about 
eighty  years,  no  increase  in  the  normal  proportion  of  C02  in  free  air 
has  been  observed.  This  is  due  to  the  constant  removal  of  CO,  from 
the  air  by  plants,  the  green  pigment  of  which,  chlorophyll,  decomposes 
C02  under  the  influence  of  sunlight,  retaining  the  carbon  in  organic 
combination,  and  returning  oxygen  to  the  air. 

Action  on  the  Economy. — An  animal  introduced  into  an  atmosphere  of 
pure  CO2  dies  almost  instantly,  and  without  entrance  of  the  gas  into  the  lungs, 
death  resulting  from  spasm  of  the  glottis,  and  consequent  apnopa. 

When  the  proportion  of  O  is  not  diminished,  the  poisonous  action  of  CO, 
is  not  as  manifest,  in  equal  quantities,  as  when  the  air  is  poorer  in  oxygen. 
An  animal  will  die  rapidly  in  an  atmosphere  composed  of  21  per  cent.  O,  59  pt-r 
cent.  N,  and  20  per  cent.  CO2  by  volume;  but  will  live  for  several  hours  in 
an  atmosphere  whose  composition  is  40  per  cent.  O,  37  per  cent.  N,  23  per  cent. 
C02.  If  CO2  is  added  to  normal  air,  of  course  the  relative  quantity  of  O  is 
slightly  diminished,  while  its  absolute  quantity  remains  the  same.  This  is 
the  condition  of  affairs  existing  in  nature  when  the  gas  is  discharged  into 
the  air.  Under  these  circumstances  an  addition  of  10-15  per  cent,  of  CO2 
renders  an  air  rapidly  poisonous,  and  one  of  5-8  per  cent,  will  cause  the 
death  of  small  animals  more  slowly.  Even  a  less  proportion  than  this  may 
become  fatal  to  an  individual  not  habituated. 

When  present  in  large  proportion,  CO2  produces  immediate  loss  of  muscular 
power,  and  death  without  a  struggle;  when  more  dilute,  a  sense  of  irritation  of 
the  larynx,  drowsiness,  pain  in  the  head,  giddiness,  gradual  loss  of  muscular 
power,  and  death  in  coma. 

If  the  CO2  present  in  air  is  produced  by  respiration,  or  combustion,  the 
proportion  of  O  is  at  the  same  time  diminished,  and  much  smaller  absolute 
and  relative  amounts  of  the  poisonous  gas  will  produce  the  effects  mentioned 
above.  Thus,  an  atmosphere  containing  in  volumes  19.75  per  cent.  O,  74.25 
per  cent.  N,  6  per  cent.  CO2,  is  much  more  rapidly  fatal  than  one  composed 
of  21  per  cent.  O,  59  per  cent.  N,  20  per  cent.  CO2.  With  a  corresponding 
reduction  of  O,  5  per  cent,  of  C02  renders  an  air  sufficiently  poisonous  to 
destroy  life;  2  per  cent,  produces  severe  suffering;  1  per  cent,  causes  great 
discomfort,  while  0.1  per  cent.,  or  even  less,  is  recognized  by  a  sense  of  closeness. 

The  treatment  in  all  cases  of  poisoning  by  CO2  consists  in  the  inhalation 
of  pure  air  (to  which  an  excess  of  O  may  be  added),  aided,  if  necessary,  by 
artificial  respiration,  the  cold  douche,  galvanism,  and  friction. 

Detection  of  Carbon  Dioxide  and  Analysis  of  Confined  Air. — Carbon 
dioxide,  or  air  containing  it,  causes  a  white  precipitate  when  caused  to  bubble 


ESTERS — COMPOUND   ETHERS  275 

through  Jime  or  baryta  water.  Normal  air  contains  enough  of  the  gas  to 
form  a  scum  upon  the  surface  of  these  solutions  when  exposed  to  it. 

It  was  at  one  time  supposed  that  air  in  which  a  candle  continued  to 
burn  was  also  capable  of  maintaining  respiration.  This  is,  however,  by  no 
means  necessarily  true.  A  candle  introduced  into  an  atmosphere  in  which 
the  normal  proportion  of  0  is  contained,  burns  readily  in  the  presence  of 
8  per  cent,  of  CO2;  is  perceptibly  dulled  by  10  per  cent.;  is  usually  ex- 
tinguished with  13  per  cent.;  always  extinguished  with  16  per  cent.  Its  ex- 
tinction is  caused  by  a  less  proportion  of  CO2,  4  per  cent.,  if  the  quantity  of  O 
be  at  the  same  time  diminished.  Moreover,  a  contaminated  atmosphere  may 
not  contain  enough  CO2  to  extinguish,  or  perceptibly  dim  the  flame  of  a 
candle,  and  at  the  same  time  contain  enough  of  the  monoxide  to  render  it 
fatally  poisonous  if  inhaled. 

The  presence  of  CO2  in  a  gaseous  mixture  is  determined  by  its  absorption 
by  a  solution  of  potash;  its  quantity  either  by  measuring  the  diminution  in 
bulk  of  the  gas,  or  by  noting  the  increase  in  weight  of  an  alkaline  solution. 

As  the  proportion  of  C02  in  air  is  determinable  readily  and  accurately, 
its  determination  in  a  confined  air  is  depended  upon  to  judge  of  the  res- 
pirability  of  the  air  and  the  degree  of  perfection  of  the  methods  of  ventilation 
used.  For  these  purposes  an  air  is  condemned  as  vitiated  if  it  contain  more 
than  six  parts  in  10,000  of  C02. 


ESTERS— COMPOUND  ETHERS. 

As  the  alcohols  resemble  the  mineral  bases,  and  the  organic  acids 
resemble  those  of  mineral  origin,  so  the  esters  are  similar  in  constitu- 
tion to  the  salts,  being  formed  by  tlie  double  decomposition  of  an  alco- 
hol with  an  acid,  mineral  or  organic,  as  a  salt  is  formed  by  double 
decomposition  of  an  acid  and  a  mineral  base,  the  radical  playing  the 
part  of  an  atom  of  corresponding  valence: 

K'  )Q  (NO,)   )  0  H  )  Q  (N02 

H    f  °  H  f  °  H  f  C  K' 

Potassium    hydroxide.        Nitric    acid.  Water.  Potassium    nitrate. 

(C2H5)'  )  0  (NO,)  )  0  H  )  (NO,)   /  0 

Hf°  H  f°  Hf°  «3»VrC 

Ethyl   hydroxide  Nitric    acid.  Water.  Ethyl   nitrate 

(alcohol).  (nitric    ether). 

Therefore  the  esters  are  substances  derived  from  acids  by  par- 
tial or  complete  substitution  of  an  alkyl  or  alkyls  for  the  basic 
hydrogen  of  the  acid. 

Some  of  the  esters  still  contain  a  portion  of  the  acid  hydrogen 
which,  being  replaceable  by  another  radical  or  by  a  metal,  com- 
municates acid  qualities  to  the  substance,  which  is  at  the  same  time 
an  ester  and  a  true  acid.  Such  esters  are  the  counter-parts  of  the 
acid  salts.  Or  di-  and  polyhydric  alcohols,  in  combining  with  acids 
of  inferior  basicity,  may  form  esters  which  still  retain  alcoholic 
hydroxyls,  and  which  are,  therefore,  alcohol-esters. 


276  TEXT-BOOK   OF"  CHEMISTRY 


ESTERS  OF  THE  MONOHYDRIC  ALCOHOLS. 

These  esters  are  produced: 

(1)  By  the  action  of  the  acid  upon  the  alcohol: 

H2S04+CH3.CH2OH=CH3.CH2.HS04+H20 ;  or 
H2S04+2CH3.CH2OH=  ( CH3.CH2)  2S04j+2H20 

(2)  By  the  action  of  the  corresponding  haloid  esters  upon  the 
silver  salt  of  the  acid: 

AgNO,+C2HBI=AgI+C2HB.N08 

(3)  By  the  action  of  the  acidyl  chlorides  upon  the  sodium  deriva- 
tives of  the  alcohols,  and  in  some  instances  upon  the  alcohols  them- 
selves : 

C2H3O.Cl+C2H5.O.Na=NaCl+C2H302.C2H5 

All  esters  are  decomposed  into  acid  and  alcohols  by  the  action  of 
water  at  high  temperatures,  or  of  caustic  potash  or  soda : 

( C2H5 )  N03+KOH=KN03+C2H5OH 

As  this  decomposition  is  analogous  to  that  utilized  in  the  manu- 
facture of  soap  (p.  282),  it  is  known  as  saponification,  and  whenever 
an  ester  is  so  decomposed  it  is  said  to  be  saponified.  When  the  de- 
composition is  effected  by  H20  the  free  acid  and  the  alcohol  are 
formed,  and  it  is  known  as  hydrolysis  (p.  64)  : 

( C2H5)  C2H302+H20=C2H5.OH+H.C2H302 

This  reaction  is  reversible  and  therefore  does  not  proceed  to  com- 
pletion. Starting  with  the  ester  it  is  saponified  according  to  the 
equation  until  equilibrium  is  established,  but  starting  with  alcohol 
and  acid  the  reaction  proceeds  according  to  the  equation  read  from 
right  to  left  until  the  same  condition  is  reached. 

Ethyl  Nitrate— Nitric  ether—  ^  |  0— 91.— A  colorless  liquid; 
has  a  sweet  taste  and  bitter  after-taste;  sp.  gr.  1.112  at  17°;  boils  at 
85  ° ;  gives  off  explosive  vapors.  Prepared  by  distilling  a  mixture  of 
HN03  and  C2H60  in  the  presence  of  urea. 

Ethyl  Nitrite— Nitrous  ether—  J™  I  0— 75— is  prepared  by  di- 
recting nitrous  fumes  into  alcohol,  contained  in  a  retort  connected 
with  a  well-cooled  receiver. 

It  is  a  yellowish  liquid ;  has  an  apple-like  odor,  and  a  sharp, 
sweetish  taste:  sp.  gr.  0.947;  boils  at  18°;  gives  off  inflammable 
vapor;  very  sparingly  soluble  in  H.,0;  readily  soluble  in  alcohol  and 
ether.  It  is  decomposed  by  warm  H20  and  by  alkalies. 


ESTERS — COMPOUND   ETHERS  277 

Ethyl  Sulphates — (C2H5)IIS04=^  Ethyl  sulphuric  or  sulphovinic 
acid  and  (C2H5)2S04 — Ethyl  -sulphate — Sulphuric  ether. 

Monoethylic   sulphate  —  Ethyl-sulphuric  acid—  ^^'Q/  S02  —  is 

formed  as  an  intermediate  product  in  the  manufacture  of  ethylic 
ether.  It  is  a  colorless,  syrupy,  highly  acid  liquid ;  sp.  gr.  1.316 : 
soluble  in  water  and  alcohol  in  all  proportions,  insoluble  in  ether. 

It  decomposes  slowly  at  ordinary  temperatures,  more  rapidly  when 
heated.  When  heated  with  alcohol,  it  yields  ethylic  ether  and  H2S04. 
When  heated  with  H20,  it  yields  alcohol  and  H2S04.  It  forms  crys- 
talline salts,  known  as  sulphovinates,  or  sulphethylates,  one  of 
which,  sodium  sulphovinate  (C2H5)NaS04,  has  been  used  in  medi- 
cine. It  is  a  white,  deliquescent  solid ;  soluble  in  H20. 

Ethyl  Sulphate— (C2H5)2S04— the  true  sulphuric  ether,  is  ob- 
tained by  passing  vapor  of  S03  into  pure  ethylic  ether,  thoroughly 
cooled.  It  is  a  colorless,  oily  liquid ;  has  a  sharp,  burning  taste,  and 
the  odor  of  peppermint;  sp.  gr.  1.120.  It  cannot  be  distilled  without 
decomposition.  With  H20  it  forms  sulphovinic  acid. 

Sulphurous  and  Hyposulphurous  Esters. — These  compounds  have 
recently  assumed  medical  interest  from  their  relationship  to  mer- 
captan,  sulphonal  and  a  number  of  aromatic  derivatives  used  as 
medicines. 

There  exist  two  isomeric  sulphurous  acids  (p.  89),  both  of  which 
yield  neutral  esters,  but  only  one  of  which,  the  unsymmetrical 

O//S\OH'  f°rms  acid  esters.  These  acid  esters  are  known  as  sul- 
phonic  acids.  (See  Aromatic  sulphonic  acids,  mercaptan,  sulphones, 
sulphonal.) 

Diethyl  Sulphite — (C2H5)2S03 — is  produced  by  the  action  of 
thionyl  chloride  on  absolute  alcohol: 

SOC122C2H5OH=S03  ( C2H5)  2+2HCl. 

It  is  a  colorless  liquid,  having  a  powerful  odor :  sp.  gr.  1.085,  boils 
at  161°.  H20  decomposes  it  into  alcohol  and  sulphurous  acid. 

Ethyl  Sulphonic  Acid— S02^^5  —is  formed  by  the  action  of 
ethyl  iodide  on  potassium  sulphite : 

C2H5I+S03K2=C2H5.S02OK+KI 

It  forms  salts  and  esters. 

Sulphinic  Acids — are  the  acid  esters  of  hyposulphurous  acid 
SOc^Qjj  and  are  analogous  to  the  sulphonic  acids. 

Orthoformic  esters  are  produced  by  heating  chloroform  with 
sodium  ethylate  or  by  adding  sodium  to  a  mixture  of  chloroform, 
ethyl  alcohol  and  ether : 

CHCl3+3C2H5ONa=CH(OC2H5)3+3NaCl 
They  are  colorless  liquids  used  in  certain  syntheses. 


278  TEXT-BOOK   OF    CHEMISTRY 

Ethyl  Acetate— Acetic  ether— c*?{°  t  O— is  obtained  by  distill- 
ing a  mixture  of  sodium  acetate,  alcohol  and  H2S04;  or  by  passing 
carbon  dioxide  through  an  alcoholic  solution  of  potassium  acetate : 

CH3.COOK+CH3.CH2OH+C02=KHC03+CH3.COO.C2H5 

It  is  a  colorless  liquid,  has  an  agreeable,  ethereal  odor:  boils  at 
74°;  sp.  gr.  0.92  at  15° ;  soluble  in  6  pts.  water,  and  in  all  proportions 
in  methyl  and  ethyl  alcohols  and  in  ether ;  a  good  solvent  of  essences, 
resins,  cantharidin,  morphine,  gun  cotton,  and  in  general,  of  sub- 
stances soluble  in  ether ;  burns  with  a  yellowish-white  flame.  Chlorine 
acts  energetically  upon  it,  producing  products  of  substitution,  vary- 
ing according  to  the  intensity  of  the  light  from  C4H6C1202  to  C4C1802. 

Ethyl  Aceto-acetate  —  Aceto-acetic  ester  —  CH3.CO.CH2.COO- 
(C2H5) — is  the  most  important  representative  of  the  class  of  y#-ketonic 
acid  esters,  which  are  important  synthetic  reagents.  It  is  prepared 
by  dissolving  6  pts.  of  metallic  sodium  in  200  pts.  of  anhydrous  ethyl 
acetate,  distilling  off  the  excess  of  the  ester,  mixing  the  residue  with 
50  per  cent,  acetic  acid  in  slight  excess,  decanting  the  oil  which 
separates,  and  fractioning. 

The  formation  of  aceto-acetic  ester  in  this  process  occurs  in  several 
reactions,  the  sum  of  which  may  be  expressed  by  the  equation: 

2CH3.COO(C2H5)=CH3.CO.CH2.COO(C2H5)+CH3.CH2OH 

two  molecules  of  ethyl  acetate  forming  one  molecule  of  aceto- 
acetic  ester  and  one  of  ethylic  alcohol.  In  one  stage  of  the  reaction 
sodium  acts  upon  ethyl  acetate  to  form  ethyl  acetyl-sodacetate, 
sodium  ethylate  and  hydrogen: 

2CH3.COO(C2H5)+Na2=CH3.CO.CHNa.COO(C2H5)  + 
C2H5.O.Na+H2 

In  another,  sodium  ethylate  acts  upon  ethyl  acetate  to  form  ethyl 
acetyl-sodacetate  and  ethylic  alcohol: 

2CH3.COO  ( C2H5)  +C2H5.O.Na=CH3.CO.CHNa.COO  ( C2H5)* 
+2CH3.CH2OH 

and,  when  the  operation  is  properly  conducted,  little  or  no 
hydrogen  is  evolved,  because  that  produced  in  the  above  reaction  acts 
with  sodium  upon  ethyl  acetate  to  form  sodium  ethylate : 

CH3.COO(C2H5)+Na2+H2=2C2H5.O.Na 

The  aceto-acetic  ester  is  liberated  from  its  sodium  derivative  by 
acetic  acid : 

CH3.CO.CHNa.COO(C2H5)+CH3.COOH=CH3.COONa 
+CH3.CO.CH2.COO  ( C2H5) 

Aceto-acetic  ester  is  a  colorless  liquid,  having  a  pleasant  odor, 
b.  p.  181°,  almost  insoluble  in  water,  and  much  more  stable  than  the 
free  acid.  It  is  colored  violet  by  FeCl3. 


ESTERS — COMPOUND   ETHERS  279 

Malonic  Ester— Neutral  ethyl  malonate— COO(C2HS).CH2.COO(C2H5)  — 
is  obtained  by  the  action  of  HC1  upon  potassium  cyano-acetate,  or  malonic  acid, 
and  alcohol: 

CH2CN.COOK+2CH,.CH2OH+HC1=KC1+NH,+COO  ( C2H5 )  .CH2.COO  ( C2H5) ,  or 
COOH.CH2.COOH+2CH,.CH,OH=C60  (C2H5)  .CH2COO  ( C2H5 )  +2H20 

It  is  a  colorless  liquid,  b.  p.  198°,  sp.  gr.  1.07,  insoluble  in  water  and  in 
alkaline  solutions. 

When,  as  in  the  cases  of  aceto-acetic  and  malonic  esters,  an  ester  is 
referred  to  without  designation  of  the  contained  alkyl,  the  neutral 
ethyl  ester  is  always  understood. 

Amyl   Nitrate —  J^j?2 1  0 — obtained   by   distilling   a  mixture   of 

HN03  and  amylic  alcohol  in  the  presence  of  a  small  quantity  of 
urea.  It  is  a  colorless,  oily  liquid;  sp.  gr.  0.994  at  10°;  boils  at 
148°  with  partial  decomposition. 

Amyl  Nitrite— Amyl  nitris  (U.  S.  P.)—  cj*P  j-  0—117— prepared 

by  directing  nitrous  fumes  into  amyl  alcohol,  contained  in  a  retort 
heated  over  a  water-bath;  purifying  the  distillate  by  washing  with 
an  alkaline  solution,  and  rectifying. 

It  is  a  slightly  yellowish  liquid;  sp.  gr.  0.877;  boils  at  95°.  Its 
vapor,  which  is  orange-colored,  explodes  when  heated  to  260°.  It  is 
insoluble  in  water;  soluble  in  alcohol  in  all  proportions.  Alcoholic 
solution  of  potash  decomposes  it  slowly,  with  formation  of  potassium 
nitrite  and  ethyl  and  amyl  oxides.  When  dropped  upon  fused  potash, 
it  ignites  and  yields  potassium  valerianate. 

Cetyl  Palmitate— Cetin—  CgHg°  |  0—480— is  the  chief  constit- 
uent of  spermacetfccetaceum  (U.  S.  P.),  which,  besides  cetin,  con- 
tains esters  of  palmitic,  stearic,  myristic,  and  laurostearic  acids;  and 
of  the  alcohols:  lethol,  C12H260 ;  methol,  C14H300;  ethol,  C16H340, 
and  stethol,  C18H380. 

ESTERS  OF  DIHYDRIC  ALCOHOLS  OR  GLYCOLS. 

The  glycols  behave  as  diacid  bases  and  form  with  the  monobasic  acids 
basic  and  also  neutral  esters: 

CH2OH  CH2.OOC.CH8  CH2OOC.CH8 

CH2OH  CH.OH  CHa.OOC.CHs 

Glycol.  Glycol  mono-acetate.  Glycol  diacetate. 

The  haloid  esters  of  the  glycols  are  also  basic  or  neutral.  The  basic  com- 
pounds are  the  glycol  halohydrines,  e.g.,  CH2OH.CH2Cl=:Ethylene  chlor- 
hydrine,  produced  by  the  action  of  the  hydracids  upon  the  glycols,  or  upon 
ethylene  oxide  and  its  homologues 

The  neutral  haloid  esters  are  among  the  haloid  derivatives  of  the  paraffins, 
higher  than  the  first.  They  are  produced  by  ( 1 )  substitution  of  the  halogen  in 
the  paraffin  or  in  the  monohalogen  paraffin ;  thus  ethyl  chloride :  CH3.CH2C1  yields 


280  TEXT-BOOK   OF   CHEMISTRY 

ethylene  chloride;  CH2C1.CH2C1;  (2)  by  addition  of  the  halogens  to  the  olefines, 
thus  ethylene:  CH2:  CH2  yields  ethylene  bichloride;  CH2C1.CH,C1;  (3)  by  the 
action  of  the  hydracids  upon  the  raonohalogen  olefines,  or  upon  the  glycols,  or 
upon  the  glycol  chlorhydrines.  Thus  ethylene  bichloride  is  obtained  from 
ethylene  monochloride :  CHC1:CH2;  ethylene  glycol:  CHaOH.CH2OH;  or  ethy- 
lene chlorhydrine:  CH2OH.CH2C1.  By  this  latter  method  two  isomeres: 
CHC12.CH3  and  CH2C1.CH.C1  may  be  produced. 

The  neutral  haloid  esters  of  the  glycols  are  the  starting  points  in  the 
preparation  of  the  glycols: 

CH2Br.CH2Br+2AgOH^2AgBr+CH2OH.CH2OH 
Nascent  hydrogen  converts  them  into  the  paraffins: 
CH2C1.CH2C1+2H2=2HC1+CH3.CH3 

Ethylene  Chloride— Elayl  chloride— Dutch  liquid— CH2C1.CH2C1— is  ob- 
tained by  passing  ethylene  through  a  retort  in  which  chlorine  is  generated. 
It  is  a  colorless,  oily  liquid,  has  a  sweetish  taste  and  an  ethereal  odor;  boils 
at  84°.  It  is  capable  of  fixing  other  atoms  of  chlorine  by  substitution  to  form 
a  series  of  compounds,  the  most  highly  chlorinated  of  which  is  carbon  tri- 
chloride, C2C16. 

ESTERS  OF  THE  TRIHYDRIC  ALCOHOLS  OR  GLYCEROLS— GLYCERIDES. 

The  glycerols  behave  as  triacid  bases,  forming  three  series  of 
esters  with  the  monobasic  acids.  These  esters  are  the  mono-,  di-, 
and  triglycerides.  Moreover,  as  two  of  the  hydroxyls  of  the  alcohol 
are  in  the  primary  groups  CH2OH,  while  the  third  is  in  the  secondary 
group,  CHOH,  there  are  two  isomeres  of  each  mono-  and  diglyceride : 


CH2.C2H802 

CH2OH 

CH2.C2H,O2 

CH2.C2H30, 

CH2.C2H302 

CHOH 

CH.C2H3O2 

CHOH 

CH.C2H302 

CH.C2H8Oa 

CH2OH 

CH2.OH 

CH2.C2H,02 

CH2OH 

CH2.C2H8O2 

a-Monacetin. 

p  Monacetin. 

a-Diacetin. 

/3-DIacetin. 

Triacetin. 

The  haloid  esters  are  known  as  the  glycerol  halohydrines.  Of  the 
glycerol  esters  of  mineral  oxyacids  those  of  nitric  and  phosphoric 
acids  are  of  interest. 

Glycerol  trinitrate — Trinitroglycerol — Nitroglycerin — Glonoin— 
C3H5(NO3)3 — is  formed  by  the  action  of  a  mixture  of  H2S04  and 
HN03  upon  glycerol: 

C3H5(OH)3+3HN03=3H20+C3H5(N03)3 

It  is  an  odorless,  yellowish  oil;  has  a  sweetish  taste;  sp.  gr.  1.6; 
crystallizes  in  prismatic  needles  when  kept  for  some  time  at  0°;  fuses 
again  at  8°.  When  suddenly  heated,  or  when  subjected  to  shock  it 
is  explosively  decomposed  into  C02  ;N  ;H20  and  0.  Alkalies  saponify 
it  to  glycerol  and  a  nitrate. 

Nitroglycerol  is  mixed  with  diatomaceous  earth  and  with  other 
inert,  absorbent  substances  in  dynamite  and  in  other  high  explosives ; 
and,  combined  with  nitrocellulose,  it  forms  "smokeless  powder." 


ESTERS — COMPOUND   ETHERS  281 

It  is  used  in  medicine  as  a  cardiac  stimulant,  and,  in  overdose,  is 
an  active  poison,  producing  effects  somewhat  similar  to  those  caused 
by  strychnine. 

Spirit  of  glyceryl  trinitrate, — spirit  of  glonoin — spiritus  glycerylis 
nitratis  (U.  S.  P.),  is  an  alcoholic  solution  of  trinitroglycerol,  con- 
taining 1  per  cent. 

Glycero-phosphoric  Acid— C3H5(OH)2.O.P03H2— is  the  mono- 
glyceride  of  phosphoric  acid.  It  is  a  product  of  decomposition  of  the 
lecithins,  or  phosphorized  fats  or  may  be  formed  by  mixing  glycerol 
and  metaphosphoric  acid: 

C3H5  ( OH)  3+HP03=C3H5  ( OH)  2O.P03H2 

It  is  a  thick  syrup,  which  is  decomposed  into  glycerol  and  phos- 
phoric acid  when  heated  with  water.  It  is  a  dibasic  acid.  The 
lithium,  sodium,  potassium,  calcium  and  iron  salts  of  this  acid  are 
occasionally  used  in  medicine. 

Glycerol  Esters  of  Organic  Acids. — The  triacid  glycerol  esters 
of  the  acids  of  the  acetic  and  acrylic  series  containing  an  even  num- 
ber of  carbon  atoms  occur  in  the  animal  and  vegetable  fats  and  oils. 

Tributyrin— C3H5(O.C4H70)  3— 302— exists  in  butter.  It  may 
also  be  obtained  by  heating  glycerol  with  butyric  acid  and  H2S04. 
It  is  a  pungent  liquid,  very  prone  to  decomposition,  with  liberation  of 
butyric  acid. 

Tricaproin— C3H5(O.CaH110)s--386  —  Tricaprylin  —  C3H5(O.C8- 
H150)3 — 470— and  Tricaprin— C3H5(O.C10H190)3— 554— exist  in 
small  quantities  in  milk,  butter,  and  cocoa  butter. 

Tripalmitin — C3H5(O.ClfiH310)3 — 806 — exists  in  most  animal  and 
vegetable  fats,  notably  in  palm  oil.  It  may  also  be  obtained  by  heat- 
ing glycerol  with  8  to  10  times  its  weight  of  palmitic  acid  for  8  hours 
at  250°.  It  forms  crystalline  plates,  very  sparingly  soluble  in  alco- 
hol, even  when  boiling;  very  soluble  in  ether.  It  fuses  at  50°,  and 
solidifies  again  at  46°. 

Trimargarin — C3H5(O.C17H330)3 — 848 — has  probably  been  ob- 
tained artificially  as  a  crystalline  solid,  fusible  at  60°,  solidifiable  at 
52°.  The  substance  formerly  described  under  this  name  as  a  con- 
stituent of  animal  fats  is  a  mixture  of  tripalmitin  and  tristearin. 

Tristearin— C3H5(O.C18H350)3— 890— is  the  most  abundant  con- 
stituent of  the  solid  fatty  substances.  It  is  prepared  in  large 
quantities  as  an  industrial  product  in  the  manufacture  of  stearin 
candles,  etc.,  but  is  obtained  free  from  tripalmitin  only  with  great 
difficulty. 

In  as  pure  a  form  as  readily  obtainable,  it  forms  a  hard,  brittle, 
crystalline  mass ;  fusible  at  68  °,  solidifiable  at  61  ° ;  soluble  in  boiling 
alcohol,  almost  insoluble  in  cold  alcohol,  readily  soluble  in  ether.  . 

Triolein — C3H5(O.C18H330)3 — 884 — exists  in  varying  quantity  in 
all  fats,  and  is  the  predominant  constituent  of  those  which  are  liquid 


282  TEXT-BOOK   OP   CHEMISTRY 

at  ordinary  temperatures.  It  may  be  obtained  from  animal  fats  by 
boiling  with  alcohol,  filtering  the  solution,  decanting  after  twenty- 
four  hours'  standing;  freezing  at  0°,  and  expressing. 

It  is  a  colorless,  odorless,  tasteless  oil  ;  soluble  in  alcohol  and 
ether,  insoluble  in  water;  sp.  gr.  0.92. 

The  Neutral  Oils  and  Fats  are  mixtures  in  varying  proportions  of  the 
triglycerides  of  the  acids  of  the  acetic  and  acrylic  series,  principally  tripalmitin, 
tristearin,  and  triolein  The  first  two  of  these  are  solid  at  the  ordinary  tem- 
perature and  the  las*,  liquid.  In  the  oils  the  last  predominates,  in  the  fats 
the  former.  In  the  cold  the  oils  become  solid  (fats),  and,  on  heating,  the 
fats  become  oils.  The  fats  and  oils  are  usually  odorless,  white  or  yellow, 
unctuous  to  the  touch,  and  produce  a  translucent  stain  upon  paper.  They 
are  insoluble  in  and  lighter  than  water,  readily  soluble  in  ether,  petroleum 
ether,  benzene,  and  many  other  organic  solvents.  Although  the  oils  do  not 
mix  with  water,  and  promptly  rise  to  its  surface  after  having  been  agitated 
with  it,  an  oil  may  remain  suspended  for  a  long  time;  suspended  in  very 
minute  globules  in  an  aqueous  liquid,  if  bile,  pancreatin,  albumin,  or  other 
emulsifying  agents  be  present.  Such  a  mixture,  sometimes  practically  per- 
manent, is  called  an  emulsion. 

Like  other  esters  the  fats  and  oils  are  hydrolyzed  or  saponified  when  heated 
with  steam  or  with  a  caustic  alkali.  The  alcohol,  glycerol,  is  liberated,  and, 
if  steam  is  used,  the  fatty  acid  also;  while  if  an  alkali  is  used  a  soap  is 
formed,  which  is  a  salt  of  the  fatty  acid: 


C8H8(C18H8302),     +     3KOH     =     C3H8(OH),     -f- 
Glyceryl    oleate  Glycerol.  Potassium  oleate 

(Pat)  (Soap) 

The  sodium  soaps  are  hard,  those  of  potassium  soft.  Castile  soap  is  a 
sodium  soap,  made  from  olive  oil.  Yellow  soap  is  made  from  tallow  or  other 
animal  fat,  and  contains  about  one-third  of  its  weight  of  rosin.  Lead  plaster 
is  lead  soap. 

The  fixed  oils  are  so  called  to  distinguish  them  from  the  volatile  oils, 
more  properly  called  essences,  which  are  also  unctuous  to  the  touch,  and  render 
paper  translucent,  but  which  are  hydrocarbons,  not  esters. 

The  vegetable  oils  form  three  classes:  (1)  The  non-drying,  or  greasy  oils, 
which  remain  liquid  and  greasy  on  exposure  to  air.  Olive  oil  and  peanut  oil 
are  representatives  of  this  class.  (2)  Drying  oils,  which  dry  and  become  hard 
when  exposed  to  air.  These  oils,  which  contain  linoleic  acid,  are  used  in  making 
paints.  Linseed,  hemp,  poppy,  and  sunflower  oils  are  drying  oils.  (3)  Semi- 
drying  oils  are  intermediate  between  the  other  two  classes,  and  are  more  or 
less  drying.  In  this  class  are  cottonseed,  sesame,  rape  seed,  and  castor  oils. 
The  animal  oils,  used  for  dressing  leather,  as  lubricants  and  for  illumination, 
are  fish  oils,  whale,  and  porpoise  oil,  neat's  foot  oil,  lard  oil,  and  tallow  oil. 
Cod  liver  oil  contains,  besides  the  glycerides.  of  oleic,  myristic,  palmitic,  and 
stearic  acids,  small  quantities  of  those  of  butyric  and  acetic  acids.  It  also 
contains  certain  biliary  principles,  a  phosphorized  fat,  traces  of  iodine  and 
bromine,  probably  in  organic  combination,  a  peculiar  fatty  acid  called  gadinic 
acid,  a  brown  substance  called  gadinin,  and  two  alkaloidal  bodies:  aselline, 
C26H82N4,  and  morrhuine,  CieH27N3.  Sperm  oil  is  not  a  true  oil,  but  a  liquid 
wax;  it  contains  no  glycerides,  but  consists  mainly  of  esters  of  the  higher 
monoatomic  alcohols. 

Lecithins  —  Phosphorized  Fats.  —  These  substances  are  widely 
distributed  in  animal  and  vegetable  tissues  and  fluids,  and  are  par- 


ESTERS  —  COMPOUND   ETHERS  283 

ticularly  abundant  in  the  yolks  of  eggs,  brain,  and  nerve  tissue, 
semen,  and  blood-corpuscles  and  plasma,  where  they  probably  serve 
as  material  for  the  formation  of  the  more  complex  phosphorized 
bodies  such  as  protagon  and  the  nucleins.  The  lecithins  are  colorless 
or  yellowish,  imperfectly  crystalline  solids,  of  a  waxy  consistency, 
and  very  hygroscopic.  They  do  not  dissolve  in  water,  but  swell  up 
in  it  like  starch.  They  are  soluble  in  chloroform,  in  benzene,  and  in 
hot  alcohol  and  hot  ether.  From  alcoholic  solutions  they  crystallize 
in  fine  needles.  When  heated  with  baryta  water  or  with  acids  they 
are  decomposed  into  glycero-phosphoric  acid,  chlorine,  and  a  fatty 
acid,  usually  palmitic  or  stearic.  The  lecithins  are  therefore  deriva- 
tives of  glycero-phosphoric  acid,  in  which  the  two  remaining  hy- 
droxyls  of  the  glycerol  are  replaced  by  fatty  acid  residues,  and  one 
of  the  two  remaining  basic  hydrogen  atoms  of  the  phosphoric  acid 
is  replaced  by  the  basic  radical  of  choline,  which  is  a  quaternary 
ammonium  : 


/O.N.CH2.CH2.OH 
0:P—  OH 

\O.CH2.CH(C18H3B03).CH2(ClflH8102) 

Stearyl-palmityl    lecithin. 

From  the  above  formula  it  will  be  seen  that  the  lecithins  may 
unite  with  acids,  through  the  remaining  OH  of  the  choline,  or  with 
bases,  through  the  remaining  basic  H  of  the  phosphoric  acid,  to  form 
salts.  The  lecithins  differ  from  each  other  in  the  nature  of  the  fatty 
acids  entering  into  their  composition.  Distearyl-,  dioleyl-  and 
stearyl-palmityl  lecithins  are  known. 


ESTERS    OF    OXYACIDS— LACTIDES    AND    LACTONES. 

The  oxyacids  not  only  form  esters  with  the  alcohols  in  the  same  manner 
as  the  pure  acids,  but,  being  themselves  both  alcohol  and  acid,  they  produce 
cyclic  esters,  in  the  formation  of  which  they  play  the  part  of  alcohol  as  well 
as  that  of  acid.  The  lactides  are  formed  by  the  interaction  of  two  oxyacid 
molecules,  each  performing  the  functions  of  both  alcohol  and  acid.  The  lactones, 
which  are  formed  only  by  the  y  and  higher  oxyacids,  are  produced  from  a  single 
molecule  of  the  acid,  whose  carboxyl  and  alcoholic  groups  interact  with  each 
other.  The  following  formulae  will  indicate  the  genesis  of  the  lactides  and 
lactones: 

CH2OH  COOH 

COOH  CEUOH 


Glycollic   acid. 


CH2.COO 

COOH 

ccxr 

COO.CH2 

aCH2 

aCH2 

0CH2 

j8CH2 

yCH2OH 

yCH2. 

GlycolHde 

y  -Oxybutyric 

V  -Butyrolactone 

(Lactide). 

acid. 

(Lactone.) 

284  TEXT-BOOK   OF   CHEMISTRY 

The    y  lactones  are  formed  from  the   y    monohalogen  acids:    (1)    by  dis- 
tillation: 


COOH.CH2.CH2.CH2C1=COO.CH2.CH2.CH2-|-HC1 
(2)    By  boiling  with  H20,  KOH  or  K2CO3: 


COOH.CH2.CH2.CH2ClTf-KOH=H20+KCl+COO.CH2.CH2.CH2 

By    reduction    the    higher    lactones    yield    aldo-hexoses.      Thus    d-glucose    is 
produced  by  the  reduction  of  the  lactone  of  d-gluconic  acid: 


COO.  ( CHOH )  4.CH2+H,=CHO.  ( CHOI! )  «.CH2OH 

The  higher  oxycarboxylic  acids  readily  lose  water  arid  are  converted  into 
lactones. 

Acylation — Determination  of  Hydroxyl,  etc. — The  formation  of  esters 
by  the  introduction  of  acidyls,  referred  to  as  acylation,  is  utilized  to  determine 
the  number  of  alcoholic  or  phenolic  hydroxyls  contained  in  a  molecule.  The 
acidyls  usually  resorted  to  for  this  purpose  are  acetyl,  CH3.CO,  and  benzoyl, 
C6H5.CO;  and  the  reactions  most  frequently  employed  are  those  between  the 
substance  examined  and  the  oxide  or  chloride  of  the  acidyl.  Thus  phencl  and 
acetyl  chloride  produce  phenyl  acetate: 

CflH5.OH+CH,.COCl=C9H5.O.OC.CH8+HCl 

And  methyl  alcohol  and  benzoyl  chloride  produce  methyl  benzoate: 
H.CH2OH+CftH5.COCl=CaHB.COO  ( CH3 )  +HC1. 

The  process  of  alkylation,  i.e.,  the  replacement  of  H  in  OH  by  alkyls  to 
form  esters,  has  more  limited  application.  Alkyls  may  replace  the  H  of  OH  in 
carboxyl  COOH,  in  the  methoxyl  group  of  the  primary  alcohols,  CH2OH,  and  in 
the  phenolic  hydroxyl,  C8HVOH,  but  not  in  the  secondary  and  tertiary  alcoholic 
groups  CHOH  and  COH.  Therefore,  alkylation  may  sometimes  be  resorted  to  to 
differentiate  the  latter  hydroxyls  from  the  former. 

SULPHUR  DERIVATIVES  OF  THE  PARAFFINS. 

As  the  mineral  sulphides  and  sulphydrates  correspond  to  the 
oxides  and  hydroxides,  so  there  exist  thioethers  and  thioalcohols, 
which  are  the  counterparts  of  the  simple  ethers  and  of  the  alcohols, 
as  well  as  thioaldehydes,  thioketones  and  thioacids.  Moreover,  as 
sulphur  may  be  quadrivalent  or  hexavalent,  as  well  as  bivalent,  there 
exist  other  important  compounds,  the  sulphoxides,  sulphones  and 
sulphonic  acids,  which  have  no  oxygen  analogues. 

The  following  formulae  will  serve  to  illustrate  the  relations  of  the 
oxygen  and  thio  compounds: 

CH2OH  /CH2.CH,  COOH  /O.CH2.CH. 

O  CH8.CH 

CH,  \CH2.CH,  CHS  \O.CH2.CH, 

Ethyllc   alcohol.  Ethyl  oxide.  Acetic  acid.  Acetal. 

CH2SH  /CH2.CH,  COSH  /S.CH2.CH, 

S  CH..CH 

CH,  \CH,.CH,  CH,  \S.CH2.CH, 

Ethyllc   thloalcohol.          Ethyl  sulphide.      Thloacetlc  acid.  Mercaptal. 

Thioethers,  or  Sulphides— are  produced  by  processes  correspond- 


SULPHUR  DERIVATIVES   OF  THE   PARAFFINS  285 

ing  to  those  by  which  the  ethers  are  formed :  (1)  by  distilling  salts  of 
ethyl-sulphuric  acids  with  potassium  sulphide: 

2KS04.C2H5+K2S=S(C2H5)2+2K2S04 

(2)  By  the  action  of  alkyl  halides  upon  potassium  sulphide: 

2CH3C1+K2S=S(CH3)2+2KC1 

(3)  By  the  action  of  phosphorus  pentasulphide  upon  the  oxygen 
ethers : 

40(C2H5)2+P2S5=S(C2H5)2+2(C2H5)3P02S2 

The  last  is  a  general  method  by  which  the  thio  compounds  may 
be  obtained  from  the  corresponding  oxygen  compounds,  the  sec- 
ondary products  being  thiophosphoric  esters. 

The  thioethers  are  colorless  liquids,  insoluble  in  water,  soluble  in 
alcohol  and  ether,  of  disagreeable  odors.  They  contrast  with  the 
oxygen  ethers  chiefly  in  their  additive  power,  dependent  upon  the 
greater  valence  capacity  of  sulphur. 

Thioalcohols — Mercaptans — are  formed:  (1)  by  the  action  of  po- 
tassium sulphydrate  upon  alkyl  halides : 

KHS+CH3.CH2C1=CH3.CH2SH+KC1 

(2)  By  distilling  the  salts  of  the  acid  alkyl  sulphates  with  po- 
tassium sulphydrate: 

KS04(C2H5)  +KHS=CH3.CH2SH+K2S04 ;  and 

(3)  By  the  action  of  phosphorus  pentasulphide  upon  the  alcohol. 
The  thioalcohols  differ  in  some  of  their  general  reactions  from  the 

alcohols :  While  the  H  of  the  OH  of  alcohols  can  only  be  replaced  by 
K  and  Na  among  the  metals,  the  H  and  SH  may  be  replaced  by  the 
heavy  metals  as  well.  Thus  with  mercuric  oxide : 

2CH3.CH2SH+HgO=r(CH3.CH2S)2Hg+H20 

Such  metallic  compounds  are  called  mercaptids,  and  the  name 
"mercaptan"  (mer curium  captans),  is  due  to  the  formation  of  mer- 
cury mercaptid.  Owing  to  the  greater  valence  capacity  of  sulphur, 
the  thioalcohols  do  not  yield  thioaldehydes  and  thioacids  on  oxidation. 

Ethyl  mercaptan— Ethyl  sulphydrate— Thioalcohol— CH3.CH2- 
SH — is  prepared  industrially,  as  the  first  step  in  the  formation  of 
sulphonal,  by  the  first  of  the  general  methods  given  above.  It  is 
a  colorless  liquid,  sp.  gr.  0.8325,  boils  at  36.2°,  has  an  intensely 
disagreeable  odor,  burns  with  a  blue  flame,  is  neutral  in  reaction, 
sparingly  soluble  in  water,  soluble  in  alcohol  and  in  ether,  dissolves 
I,  S  and  P.  Potassium  and  sodium  act  upon  mercaptan  as  they  do 
upon  alcohol,  replacing  the  extra-radical  hydrogen  to  produce 
mercaptids,  or  thioethylates,  corresponding  to  the  ethylates. 

There  also  exist  mono-  and  di-thioglycols,  corresponding  to  the 


286  TEXT-BOOK   OF    CHEMISTRY 

dihydric  alcohols.     One  of  these,  monothioethylene   glycol   C2H4.- 
OH.SH,  yields  isethionic  acid  on  oxidation. 

Sulphoxides  and  Sulphones — are  products  of  oxidation  of  the 
sulphides  in  which  the  sulphur  is  quadrivalent  or  hexavalent : 

C2H6\  o  C2H6\  s_0  C2H5\     //  o 

C8H5/b  C2H5/b  C?H8/S\\0 

Ethyl   sulphide.  Ethyl   sulphoxlde.  Etbyl   sulphone. 

Other  products  of  oxidation  of  thio-compounds,  containing  the 
group  (S02)"  attached  to  a  hydrocarbon  group,  are  also  called 
sulphones. 

Sulphonic  Acids — are  acids  containing  the  group  (02S.OH)'  at- 
tached to  a  hydrocarbon  group.  The  sulphonic  acids  of  this  series 
are  formed  by  oxidation  of  the  mercaptans;  by  the  action  of  the 
paraffin  iodides  upon  the  alkaline  sulphites  or  Ag  sulphite ;  or  by 
the  action  of  sulphuric  acids  upon  alcohols,  ethers,  etc.  They  may 
be  considered  as  being  derived  from  the  unsymmetrical  sulphurous 
acid  (p.  89)  by  replacement  of  the  H  atom  by  an  alkyl;  and  are 
isomeric  with  the  monoalkyl  sulphites  (formula  below),  from  which 
they  are  distinguished  by  the  fact  that  the  latter,  being  esters,  are 
saponified  by  alkalies,  which  the  former  are  not. 

The  thioglycols  on  oxidation  also  yield  sulphonic  acids.  Isethionic 
acid,  C2H4.OH.S03H,  mentioned  above,  is  a  thick  liquid,  whose 
amido  derivative  is  taurin. 

In  the  thiosulphonic  acids,  which  only  exist  in  their  salts  and 
esters,  the  oxygen  in  the  hydroxyl  of  the  sulphonic  acids  is  replaced 
by  sulphur. 

Sulphinic  acids  bear  the  same  relation  to  hydrosulphurous  acid 
that  the  sulphonic  acids  do  to  the  unsymmetrical  sulphurous  acid : 

0\\      /H  0\\  o  /C2H,       0_s  /O.C2H6          _s  /H  _s /C2H6 

0//S\OH  O//b\OH  b\OH  b\OH  b\OH 

Unsymmetrlcal  Etbyl   sulphonic  Monethyllc  Hydrosulphurous     Etbyl  sulphinic 

sulphurous  acid.  acid.  sulphite.  acid.  acid. 

Thioaldehydes  and  their  Sulphones. — The  simple  thioaldehydes 
are  not  known,  owing  to  the  tendency  to  polymerize  which  they  pos- 
sess to  a  still  more  marked  degree  than  the  aldehydes  (p.  228).  The 
trithioaldehydes  and  their  sulphones  are  odorless,  colorless  solids. 
The  relations  of  these  compounds  are  shown  by  the  f ormulaB : 

f\ p  /H      o p  /H     >-x/CH2.0\  p-p-      Q  /CH2.S\  p.p.      _.  ~/  CH2.S02\pTT 

~C\H         ~C\H     °\CH2.0/CH'     b\CH2.S/CHj     °'b\CH2.S02/tH' 

Formic  Thloformic  Triform-  Trlthloform-  Trlmethylene 

aldehyde.  aldehyde.  aldehyde.  aldehyde.  trlsulphone. 

Thioacetals — Mercaptals — are  produced  by  the  action  of  paraffin 
iodides  upon  alkali  mercaptids,  or  by  the  action  of  HC1  upon  a  mix- 


SULPHUR  DERIVATIVES   OF  THE   PARAFFINS  287 

ture  of  aldehyde  and  mercaptan.  By  oxidation  they  yield  sulphones, 
whose,,  methylene  hydrogen  may  be  replaced  by  alkyl  groups : 

H\  r  /O.C2H5    H\  r  /S.C2H5    H\  p  /S02.C2H5        H\  r  /S02.C2H5 
H/C\O.C2H5    H/°\S.C2H5    H/C  \S02.C2H5     CH3/ u  \S02.C2H5 

Metbylene  diethyl  ether  Methylene  Methylene  diethyl  Ethldene  diethyl 

(Acetal).  rnercaptal.  sulphone.  sulphone. 

Sulphonal — Acetone  Diethyl  Sulphone — Disulphethyl-dimefhyl- 
methane — (CH3)2:C(S02C2H5)2 —  is  obtained  by  oxidizing  ethyl 
mercaptol  by  potassium  permanganate.  It  crystallizes  in  thick,  color- 
less prisms,  difficultly  soluble  in  cold  water  or  alcohol,  readily  soluble 
in  hot  water  or  alcohol,  and  in  ether,  benzene  and  chloroform.  It 
fuses  at  126  °  and  boils  at  300  °,  suffering  partial  decomposition. 

Sulphonal  contains  two  ethyl  groups,  trional  contains  three,  and 
tetronal  four.  Their  hypnotic  power  increases  with  the  number  of 
ethyl  groups  which  they  contain.  Other  ' '  sulphonals "  are  obtain- 
able from  the  corresponding  mercaptols  by  methods  similar  to  the 
above.  Among  these  is  acetone  dimethyl  sulphone,  which  contains 
no  ethyl  group,  and  has  no  hypnotic  action.  The  relations  of  these 
compounds  is  shown  by  the  following  formulae : 

CH,\p/S02.C2H6  CH3\  /S02.C2HB  C2H5\  /S02.C2H5  CH3\  r/S02.CH8 
CH8/L\S02.C2H5  C2H5/U\S02.C2H5  C2H5/  c\SO2.C2He  CH8/  L\S02.CH, 

Sulphonal.  Trional.  Tetronal.  Acetone  dimethyl 

sulphone. 

Ichthyol — is  the  Na  salt  of  a  complex  sulphonic  acid,  having  the 
empirical  formula  C28H36S306Na2,  obtained  by  the  distillation  and 
purification  of  an  ozocerite  (a  mineral  pitch).  It  is  a  dark  brown, 
pitchlike  mass,  having  a  disagreeable  odor,  soluble  in  water  and  in 
glycerol. 

Thioacids  and  their  Thioanhydrides. — In  the  thioacids  of  the 
acetic  series  the  sulphur  is  substituted  for  the  oxygen  in  the  hydroxyl. 
Thioacetic  acid,  CH3.CO.SH,  is  formed  by  the  action  of  phosphorus 
pentasulphide  upon  acetic  acid. 

Carbon  Bisulphide — CS2 — bears  the  same  relation  to  sulphothio- 

carbonic  acid,  CS\QH,  and  to  trithiocarbonic  acrd,  CS\|g,  that  car- 
bon dioxide  bears  to  carbonic  acid.  It  is  prepared  by  passing  vapor 
of  S  over  C  heated  to  redness,  is  partly  purified  by  rectification, 
and  obtained  pure  by  redistillation  over  mercuric  chloride. 

It  is  a  colorless  liquid.  When  pure  it  has  a  peculiar,  but  not 
disagreeable  odor,  the  nauseating  odor  of  the  commercial  product 
being  due  to  the  presence  of  another  sulphurated  body ;  boils  at  47  ° ; 
sp.  gr.  1.293 ;  very  volatile.  Its  rapid  evaporation  in  vacuo  produces 
a  cold  of  — 60°.  It  does  not  mix  with  H20.  It  refracts  light 
strongly. 

It  is  highly  inflammable,  and  burns  with  a  bluish  flame,  giving 
off  C02  and  S02 ;  its  vapor  forms  highly  explosive  mixtures  with  air, 


288  TEXT-BOOK   OF    CHEMISTRY 

which  detonate  on  contact  with  a  glass  rod  heated  to  250°.  Its  vapor 
forms  a  mixture  with  nitrogen  dioxide,  which  when  ignited,  burns 
with  a  brilliant  flame,  rich  in  actinic  rays. 

A  substance  also  exists,  intermediate  in  composition  between  C02 
and  CS2,  known  as  carbon  oxysulphide,  CSO,  which  is  an  inflam- 
mable, colorless  gas,  obtained  by  decomposing  potassium  thiocyanate 
with  dilute  H2S04. 

Toxicology.  —  Workmen  engaged  in  the  manufacture  of  CS2,  and  in  the  vul- 
canization of  rubber,  as  well  as  others  exposed  to  the  vapor  of  the  disulphide,  are 
subject  to  a  form  of  chronic  poisoning  which  may  be  divided  into  two  stages. 
The  first,  or  stage  of  excitation,  is  marked  by  headache,  vertigo,  a  disagreeable 
taste,  and  cramps  in  the  legs.  The  patient  talks,  laughs,  sings,  and  weeps  im- 
moderately, and  sometimes  becomes  violently  delirious.  In  the  second  stage  the 
patient  becomes  sad  and  sleepy,  sensibility  diminishes,  sometimes  to  the  extent  of 
complete  anesthesia,  especially  of  the  lower  extremities,  the  headache  becomes 
more  intense,  the  appetite  is  greatly  impaired,  and  there  is  general  weakness  of 
the  limbs,  which  terminates  in  paralysis. 

The  only  remedy  which  has  been  suggested  is  thorough  ventilation  of  the 
workshop,  and  abandonment  of  the  trade  at  the  first  appearance  of  the  symptoms. 

ORGANO-METALLIC  COMPOUNDS. 

These  are  compounds  of  organic  radicals  with  metallic  elements, 
the  best  known  being  those  of  the  alkyls  with  zinc  and  mercury. 

Zinc-methyl,  or  Zinc  Methide  —  (CH3)2Zn,  and  Zinc-ethyl,  or 
Zinc  Ethide—  (C2H5)2Zn—  are  formed  by  heating  to  130°-150° 
methyl  or  ethyl  iodide  with  excess  of  zinc  amalgam,  and  distilling 
without  contact  of  air.  They  are  colorless  liquids,  the  former  b.  p. 
46°,  sp.  gr.  1.386,  the  latter  b.  p.  118°,  sp.  gr.  1.182.  On  contact  of 
air  they  ignite  and  burn,  giving  off  dense  clouds  of  ZnO.  By  the 
moderated  action  of  air  they  produce  solid  oxyalkylates  : 


or  alcoholates:  Zn/J    S3.     The  former  are  also  produced,  along  with 

\  v/.V_/±l3 

hydrocarbons,  by  the  action  of  zinc-alkyls  upon  alcohols: 
(CH3)2Zn+H.CH2OH^CH3.O.Zn.CH3+CH4 

and   are    decomposed   by    water    with    formation    of    hydrocarbons 
and  primary  alcohols: 

CH3.O.Zn.CH3+2H20=ZnH202+H.CH2OH+CH4 

With  the  halogens  the  zinc  alkyls  react  violently  to  form  alkyl 
halides  : 

(CH3)2Zn+2Br2=2CH3Br+ZnBr2 

They  unite  with  sulphur  dioxide  to  produce  zinc  alkyl-sulphinates 
(p.  286)  : 

(C2H5)  2Zn+S02=  (0  :S  <g'H>  )  2Zn 
With  acidyl   chlorides  and  aldehydes  they   form  complex  com- 


ORGANO-METALLIC    COMPOUNDS  289 

pounds,  Vhich  are  decomposed  by  water  to  form  ketones,  or  tertiary 
or  secondary  alcohols. 

Zinc  alkyls  act  with  acidyl  chlorides  to  form  addition  products: 

/CH3 
CH3.CO.Cl+Zn(CH3)2=CH3.C— O.Zn.CH3 

\C1 

which  are  decomposed  by  H20  with  formation  of  ketones  and  hydro- 
carbons : 

/CH3 
CH3.C— O.Zn.CHs+H20=CH3.CO.CHs+Cl.Zn.OH+CH4 

\C1 

or  in  which  the  Cl  atom  may  be  replaced  by  an  alkyl  by  the  action 
of  a  second  molecule  of  the  zinc  alkyl: 

/CH3  /CH3 

CH3.C— O.Zn.CH3+Zn.(CH3)2=CH3.C— O.Zn.CH3+Cl.Zn.CH3 

\C1  \CH3 

and  this  compound  on  decomposition  by  H20  yields  a  tertiary  alco- 
hol and  a  hydrocarbon : 

/CH3  /CH3 

CH3.C— O.Zn.CH3+2H20=CH8.C— OH+Zn(OH)2+CH4 

\CH3  \CH3 

By  its  action  upon  aldehydes  the  zinc  alkyl  forms  addition  products 
similar  to  those  produced  with  the  acidyl  halides,  the  halogen  being, 
however,  replaced  by  H : 

/CH3 

CH3.CHO+Zn(CH3)2=CH3.C— O.Zn.CH3 

\H 

which  on  decomposition  by  water  yields  secondary  alcohols : 

/CH8  /CH8 

CH3.C— O.Zn.CH3+H20=CH3.C.— OH+HO.Zn.CH3 

\H  \H 

Carbonyl  chloride  reacts  with  the  zinc  alkyl  to  form  acidyl 
chlorides: 

2COCl2+Zn(CH3)2=2CH3.CO.Cl+ZnCl2 
which  with  water  produces  the  corresponding  acids: 
CH3.CO.C1+H20=CH3.CO.OH+HC1 

Organo-Magnesium  Compounds. — Compounds  corresponding  to 
the  zinc  alkyls :  R2Mg  are  known,  and  are  equally  unstable  and  diffi- 
cult to  handle.  The  mixed  organo-halide  compounds  of  Grignard  of 
the  type  R.Mg.X,  in  which  R  is  a  univalent  hydrocarbon  radical, 
aliphatic  or  cyclic,  and  X  a  halogen,  are  more  convenient  to  handle 
and  give  better  results  in  the  syntheses  of  hydrocarbons,  alcohols  and 
monobasic  acids  (pp.  203,  212,  251).  Magnesium  turnings  in  the 
presence  of  anhydrous  ether  react  with  alkyl  bromides  and  iodides 
to  form  gray  semi-crystalline  compounds  which  are  etherates  of 
alkyl  magnesium  halides,  "oxonium"  compounds,  in  which  the 

R\    /x 

oxygen  is  quadrivalent  and  basic,  of  the  type        0  ,  in  which 

R  /    \MgR' 


290  TEXT-BOOK   OF   CHEMISTRY 

K.  R.  are  the  alkyls  of  the  ether,  R'  that  of  the  alkyl  halide,  and 
X  the  halogen.  These  in  turn  are  decomposed  with  the  formation 
of  alkyl  magnesium  halides  of  the  type:  R.Mg.X.  Or  the  reaction 

R\     /R'  R\    /R' 

may  take  place  in  two  stages:  R'X+R20=      0       ,  and        0 

R/    \X  R/    \X 

-f  Mg=R'.Mg.X-|-R20,  the  ether  behaving  as  a  catalyser.  The  re- 
action does  not  occur  in  the  simple  form:  R'X-f-Mg=R'.Mg.X,  as  it 
does  not  occur  in  the  absence  of  ether,  as  when  benzene,  petroleum 
ether,  etc.  are  used  as  solvents. 

Carbonyl  chloride  and  alkyl  magnesium  halides  interact  to  pro- 
duce tertiary  alcohols: 

COCl2+3CH3.MgCl=(CH3)3:C.O.MgCl+2MgCl2,   and 
( CH3)  3!C.O.MgCl+H20=  ( CHS)  a:COH+HO.MgCl 

Water  and  compounds  containing  hydroxyls,  such  as  alcohols,  acids, 
phenols,  etc.,  decompose  the  organo-halide  magnesium  compounds 
with  formation  of  the  corresponding  hydrocarbons,  according  to  the 
equations : 

R.Mg.X+H20=RH+MgO+HX,  or 
R.Mg.X+R.CH2OH=R.CH3+R.O.MgX,    or 
R.Mg.X+R.COOH=:RH+R.COO.Mg.X,  or 
R.MgX+C6H5.OH=C6H5.H.+R.O.Mg.X 

The  compounds  R.O.Mg.X  and  R.COO.Mg.X  are  themselves  hydro- 
lyzed  by  water  with  regeneration  of  the  corresponding  alcohol  or 

acid:  R.O.Mg.X+H20=R.OH+HO.Mg.X,  and 

R.COO.Mg.X+H20=R.COOH+HO.Mg.X 

The  alkyl  magnesium  compounds  act  upon  substances,  such  as  alde- 
hydes and  ketones,  containing  an  oxygen  atom  doubly  linked  to 
carbon,  to  form  condensation  products  of  the  types  R.O.Mg.X  or 
R.CH. R.O.Mg.X.  These  condensed  compounds  are  readily  hydro- 
lyzed  by  dilute  acids  to  magnesium  hydrohalides,  and  a  hydroxyl  is 
attached  to  the  carbon  in  the  position  of  the  oxygen  linkage.  The 
above,  known  as  the  Grignard  reactions,  are  extensively  used  in  the 
preparation  of  alcohols,  both  aliphatic  and  cyclic.  The  reaction  with 
formic  aldehyde  differs  from  that  with  its  superior  homologues.  The 
phenyl  magnesium  halides  are  readily  oxidized  by  the  passage  of  air 
through  their  ethereal  solutions  with  formation  of  condensed  com- 
pounds of  the  type  R.O.Mg.X  which  when  hydrated  yield  phenols. 

The  organo-magnesium  halides  react  with  esters  of  monobasic 
acids,  except  formic,  with  the  formation  of  condensed  products  which 
on  hydrolysis  produce  tertiary  alcohols: 

2R'.Mg.X+R.COO(C2H5)=:R.C  \™gX  +C2H5.O.Mg.X,  and 
R.C.  {£;f gX  +H20=  £,      COH+HO.Mg.X 


NITROGEN   DERIVATIVES   OF   THE   PARAFFINS  291 

Ethyl  formate  under  like  conditions  yields  a  secondary  alcohol: 
2R.Mg.X+H.COO(C2H5)=R.CH  <£MgX +C2H5.O.Mg.X,  and 
R.CH  \R  Mg<X  +H20=R.CHOH.R+HO.Mg.X 

By  operating  at  — 50  °  a  reaction  is  obtained  between  equal  molecules 
with  formation  of  an  aldehyde: 

R.Mg.X+H.COO(C2H5)=R.CHO+C2H5.O.Mg.X 

The  esters  of  dibasic  acids  behave  in  the  same  manner  with  formation 
of  ditertiary  glycols: 

5).CH2.COO(C2H5)  =  x-M^\  C.CH2.C ^Mg-X 

+2C2H5O.Mg.X,  and 
C.CH2.C  (£Mg-X  +2H20=  HR°2>  C.CH2.C  /gf  +2HO.Mg.X 

By  passing  C02  through  solutions  of  the  alkyl  magnesium  halides, 
compounds  of  the  type  R.COO.MgX  are  precipitated,  which  when 
hydrolyzed  at  low  temperatures  produce  monobasic  acids  (p.  251). 
But  with  phenyl  magnesium  halides,  the  principal  final  products  are 
alcohols. 

The  reactions  between  acidyl  chlorides  or  anhydrides  and  alkyl 
magnesium  halides  are  violent.  When  moderated  by  ice  they  result 
in  the  formation  of  tertiary  alcohols  (p.  213). 

The  organo-magnesium  halides  condense  with  nitriles  according 
to  the  equation : 

R.Mg.X+R'.CN=RR'  :C  :N.Mg.X 

and  the  products  produce  ketones  by  hydrolysis: 

R.R'  :C  :N.Mg.X+2H20=R.CO.R'+NH3+HO.Mg.X 
But  .with  isonitriles  condensed  products  are  formed : 

R.Mg.X+R'.N^C=R'.N=:C  <^*x 

which  when  hydrolyzed  produce  imines: 

R/N  :C  /Mg-x  +H20=R'.N  :CH.R+HO.Mg.X 

Alkyl  magnesium  halides  act  upon  amides  to  produce  aldehydes 
or  ketones  (pp.  227,  234). 

Grignard's  compounds  react  with  ammonia,  amines  (including 
aniline)  and  phenyl  hydrazine  with  the  formation  of  a  hydrocarbon 
and  of  compounds  of  the  types:  H2N.Mg.X;  R.HN.Mg.X; 
R.R'.N.Mg.X;  C6H5.N(MgX).NH(MgX),  which  are  known  as 
Meunier's  compounds. 

NITROGEN  DERIVATIVES  OF  THE  PARAFFINS. 

Speaking  strictly,  the  only  nitrogen  derivatives  of  the  paraffins 
are  the  nitriles,  derived  from  the  paraffins  by  substitution  of  N  for 
H3,  as  CH3.CN,  from  CH3.CH3  and  the  diazo  paraffins,  (N2)"CH.CH3, 


292  TEXT-BOOK   OF    CHEMISTRY 

but  the  compounds  derivable  from  the  paraffins  and  from  their  oxida- 
tion products  by  substitution  of  nitrogen  containing  groups,  N02, 

NO,  NH2,  NH,  NOH,  -    -N:N ,  and  =N.N=,  are  numerous, 

varied  and  important. 

NITROPARAFFINS. 

The  univalent  group  (N02)  is  designated  by  the  syllable  nitro  in 
the  names  of  compounds  containing  it. 

The  mononitroparaffins — isomeric  with  the  nitrous  esters  are  de- 
rived from  the  paraffins  by  the  substitution  of  N02  for  an  atom  of 
hydrogen,  and  are  distinguished  as  primary,  secondary  and  tertiary, 
in  the  same  manner  as  the  corresponding  alcohols,  according  as  the 
N02  is  united  to  CH2  (CH3  in  nitromethane),  or  CH,  or  C.  They  are 
formed  by  the  action  of  the  alkyl  iodides  upon  silver  nitrite : 

CH3I+AgN02=AgI+CH3N02 

They  are  isomeric  with  the  nitrous  esters:  CH3.CH2.N((o=mono- 
nitroethane,  and  CH3.CH2.ON  :0=Ethyl  nitrite.  These  isomeres  may 
be  distinguished  by  the  action  of  KOH,  which  saponifies  the  esters: 

C2H5ON  :0+KOH=KON  :0-fCH3.CH2OH 

but  has  no  action  upon  the  nitroparaffins. 

Nascent  hydrogen  converts  them  first  into  hydroxylamine  com- 
pounds: CH3.N02+2H2=CH3.NH.OH-fH20,  which  are  in  turn 
further  reduced  to  monamines,  or  amidoparaffins : 

CH3.NH.OH+H2=NH2.CH3+H20 

AMINES  AND  AMMONIUM  DERIVATIVES. 

The  amines  are  compounds  derived  from  ammonia  by  the  substi- 
tution of  hydrocarbon  (non-acid)  radicals  for  a  part  or  all  of  its 
hydrogen. 

They  are  classified  into  monamines,  derived  from  a  single  mole- 
cule of  ammonia,  diamines,  derived  from  two  such  molecules,  and 
triamines,  derived  from  three. 

MONAMINES  AND     THEIR  DERIVATIVES. 

The  monamines  are  primary,  secondary,  or  tertiary,  as  one,  two, 
or  three  of  the  hydrogen  atoms  of  ammonia  have  been  replaced. 
They  are  also  distinguished  as  amine,  imine,  and  nitrile  bases.  When, 
in  secondary  or  tertiary  amines,  the  substituted  radicals  are  alike  the 
amines  are  designated  as  simple,  when  the  radicals  are  different  the 
amines  are  mixed.  The  primary  monamines,  containing  the  group 
NH2,  an-  amido-paraffins ;  while  the  secondary,  containing  the  group 


AMINES  AND  AMMONIUM   DERIVATIVES  293 

NH,  are  imido-paraffins.  The  monamines  have  the  algebraic  for- 
mula, NCfiHsw-hs 

A  nomenclature  similar  to  the  above  is  also  used  in  speaking  of 
nitrogen  in  other,  more  complex,  organic  compounds.  It  is  said  to  be 
in  primary  combination,  or  as  amide,  or  amine  nitrogen,  when  in  the 
amido,  or  amino  group  (NH2)',  in  secondary  combination,  or  as 
imide,  or  imine  nitrogen,  when  in  the  imido,  or  imine,  group  (NH)", 
and  in  tertiary  combination,  or  as  nitrile  nitrogen,  when  in  the  form 
N"'.  Azo-,  diazo-,  and  hydrazo-  nitrogen  is  in  the  forms  — N:N — 
and  =N.N=. 

The  monamines  are  sometimes  called  compound  ammonias,  from 
their  resemblance  to  ammonia  in  their  chemical  properties,  as  well  as 
from  their  origin.  They  combine  with  water  to  produce  quaternary 
ammonium  hydroxides,  similar  in  constitution,  alkalinity,  and 
basicity  to  ammonium  hydroxide ;  and  with  acids,  without  elimination 
of  hydrogen,  to  form  salts,  similar  to  the  ammoniacal  salts. 

The  aliphatic  monamines  are  the  most  simply  constituted  of  a 
great  variety  of  nitrogen  derivatives,  including  the  primary  mon- 
amides,  the  diamides,  such  as  urea,  and  the  vegetable  alkaloids,  which 
have  this  in  common  with  the  amines,  that  they  are  basic  in  character, 
and  in  combining  with  acids,  form  salts  in  the  same  manner  as 
ammonia  does,  i.e.,  by  change  of  the  nitrogen  valence  from  three  to 
five,  and,  consequently,  without  elimination  of  hydrogen ;  thus : 


/H 
N—  H 
\H 

Ammonia. 

/H 
H2=N—  H 
\C2H302 

Ammonium 
acetate. 

/H 
N—  H 
\CH3 

Monomethyl- 

aniine. 

/CH8 
H2=N—  CH8 
\C1 

Dimethylammo- 
niuin  chloride. 

NH2  NH2  CH2  CHa 

I      •  I  X\  /\ 

CO  CO  H2C         CH2  H2C        CH2 

NH2  N— NO,  H2C        CH2  H2C        CH2 

\X  \/ 

N  N 

I  /\\ 

H  Cl    H2 

Urea.  Urea  nitrate?  Piperidine.  Piperidine   hydrochloride. 

The  naming  of  these  compounds  has  been  the  subject  of  much  discussion. 
As  the  substances  formed  by  the  union  of  ammonia  with  acids  are  regarded  as 
salts  of  ammonium,  not  of  ammonia,  so  these  compounds  are  not  salts  of  urea, 
piperidine,  morphine,  etc.,  but  salts  of  hypothetical  bases,  containing  a  quin- 
quivalent nitrogen  atom,  which  in  the  free  base  is  trivalent.  The  names: 
ureium  nitrate,  piperidium  chloride,  morphium  sulphate,  etc.,  are  therefore  the 
analogues  of  ammonium  acetate  and  dimethylammonium  chloride.  For  the 
chlorine,  bromine,  and  iodine  compounds  the  names:  piperidine  hydrochloride, 
morphine  hydrobromide,  quinine  hydroiodide,  etc.,  may  be  conveniently  retained, 
they  being  regarded  as  the  free  bases,  plus  hydrogen,  plus  the  halogen. 


294  TEXT-BOOK   OF   CHEMISTRY 

The  following  formulas  indicate  the  constitution  of  the  amines 
and  their  hydroxides  and  salts: 


/C2H6 
N—  H 
\H 

/CH, 
N—  C2H5 
\H 

/CH, 
N—  CH, 
\CH, 

(CH,)4N.OH 

(CVH.J.N.Cl 

Bthylamine. 
(Primary). 

Methyl- 
ethylaraine. 
(Secondary). 

Trimetbyl- 
amine. 
(Tertiary). 

Tetramethyl 
ammonium 
hydroxide. 

Tetrethyl 
ammonium 
chloride. 

The  primary  monamines,  the  hydramines,  and  the  diamines  may 
also  be  considered  as  derived  from  the  monohydric  and  dihydric 
alcohols  by  substitution  of  NH2  for  OH. 

CH,  CH,  CH2OH        CH2OH          CH2NHa 

I  I  I  I  I 

CH2OH         CH2NH2         CH2OH        CH2NH2        CH2NH2 

Alcohol.          Monamlne.  Glycol.         Hydramine.          Diamine. 

The  primary  monamines  are  formed:  (1)  by  distilling  the  iso- 
cyanic  esters  with  caustic  potash: 

CO  :N.C2H5+2KOH=NH2.C2H5+C03K2 

(2)  By  heating  the  alkyl  iodides,  or  the  nitric  esters   with  alco- 
holic ammonia: 

C2H,I+NH3=NH2.C2H5+HI,  or 
C2H5.N03+NH3=NH2.C2H5+HN03 ; 

(3)  By  the  action  of  nascent  H  in  alcoholic  solution  upon  the 
nitriles : 

CH3.CN+2H2=NH2.C2H5 

(4)  By  the  action  of  nascent  H  upon  the  nitroparaffins : 

CH3.N02+3H2=NH2CH3+2H20 

(5)  From  the  monamides  of  the  fatty  series  monoamines,  con- 
taining one  atom  of  carbon  less  than  the  amide,  are  formed  by  the 
action  of  bromine  and  potassium  hydroxide.    The  reaction  occurs  in 
two  stages.    First  a  bromide  is  produced: 

C2H5.CO.NH2+Br2+KOH=rC2H5.CO.NHBr+KBr+H20 

which  is  in  turn  converted  into  the  amine  with  loss  of  the  car- 
bonyl  group : 

C2H5.CO.NHBr+3KOH=rC2H5.NH2+C03K2+H20-f-KBr 

The  secondary  monamines  are  formed,  as  intermediate  products, 
by  the  action  of  the  alkyl  iodides  upon  the  primary  monamines  in  the 
presence  of  excess  of  ammonia.  The  alkyl-ammonium  iodide  is  first 
produced : 

NH2.C2H5+C2H5I=NH  ( C2H5)  2HI 

and  this  reacts  with  the  ammonia : 

NH(C2H6)2HI+NH3=NH(C2H6)2+NH4I 


AMINES   AND  AMMONIUM  DERIVATIVES  295 

The  final  products  of  the  reaction  are  the  tetrammonium  iodides: 
N(C2H5)4L 

The  tertiary  monamines  are  obtained  by  the  dry  distillation  of 
the  quaternary  ammonium  hydroxides,  iodides,  or  chlorides: 

N(C2H5)J=N(C2H5)3+C2H5I 

or  by   heating  the   primary   or   secondary   amines   with   excess   of 
potassium  alkyl  sulphate: 

NH(CH3)2+CH3K.S04=N(CH3)3+KHS04 

The  primary  and  secondary  amines  react  with  esters  of 'the  mono- 
carboxylic  acids  to  form  alcohols  and  primary  or  secondary  amides. 
Thus  methylamine  and  methyl  acetate  produce  ethyl  alcohol  and 
acetamide : 

H2N.CH3+CH3.COO  ( CH3)  =CH3.CH2OH+H2N.  ( CO.CH3) 

The  primary  monamines,  when  warmed  with  chloroform  and  alco- 
holic potash,  yield  carbylamines,  isocyanides,  or  isonitriles: 

NH2.C2H5+CHC13+3KOH=CN.C2H5+3KC1+3H20 

(See  Chloroform,  test  1,  p.  206.) 

When  ethereal  solutions  of  primary  monamines  and  of  carbon 
disulphide  are  evaporated,  a  residue  is  obtained  which,  when  heated 
in  aqueous  solution  with  AgN03,  or  FeCl3,  or  HgCl2  forms  a  sul- 
phide of  the  metal  and  a  "mustard  oil,"  having  a  pungent  odor. 
This  is  Hoffman's  test  for  primary  monamines. 

Methylamine — H2N.CH3 — is  a  colorless,  inflammable  gas,  having 
a  fishy,  ammoniacal  odor.  Very  soluble  in  water  (1,154  volumes  in 
one  at  12.5°),  forming  a  highly  caustic  and  alkaline  solution.  It 
neutralizes  acids  with  formation  of  methyl  ammonium  salts,  which 
are  soluble  in  water. 

Dimethylamine — HN(CH3)2 — is  a  liquid  below  7.2°,  has  an 
ammoniacal  odor,  and  is  very  soluble  in  water.  Its  chloroplatinate 
forms  yellow  needles. 

Trimethylamine — N(CH3)3 — is  formed  by  the  action  of  methyl 
iodide  upon  NH3,  and  as  a  product  of  decomposition  of  many  organic 
substances.  It  occurs  naturally  in  combination  in  cod-liver  oil,  ergot, 
chenopodium,  yeast,  guano,  and  many  flowers.  It  is  an  oily  liquid 
below  9°,  having  a  fishy  odor,  alkaline,  soluble  in  water,  alcohol  and 
ether. 

Tetr  am  ethyl-ammonium  Hydroxide — HO.N(CH3)4 — is  a  quater- 
nary ammonium  hydroxide,  corresponding  to  ammonium  hydroxide, 
and  is  obtained  by  decomposing  the  iodide,  IN(CH3)4,  which  is 
formed  by  the  action  of  methyl  iodide  upon  trimethylamine.  It  is  a 
crystalline,  deliquescent,  caustic  solid,  not  volatile  without  decomposi- 
tion. Like  other  carbon-nitrogen  hydroxides  and  hydramines,  it 
absorbs  carbon  dioxide  from  the  air. 


296  TEXT-BOOK   OF   CHEMISTRY 


OXYAMINES    (HYDRAMINES),  DIAMINES 

The  primary  monamines  may  be  considered  as  being  derived  from 
the  monoatomic  alcohols  by  the  substitution  of  the  amido  group,  NH2, 
for  the  hydroxyl.  From  the  dihydric  alcohols,  the  glycols,  two 
classes  of  amido  compounds  may  be  similarly  derived.  One  of  these, 
the  oxyamines,  hydroxamines,  or  hydramines,  contain  a  single  amido 
group,  and  retain  an  alcoholic  hydroxyl.  In  the  diamines  both 
hydroxyls  are  replaced  by  amido  groups.  The  oxyamines  are  primary, 
secondary  and  tertiary  in  the  same  manner  as  the  monamines : 

CH2OH     CH2OH     CH2NH2     CH2(OH).CH2\  CH2(OH).CH2\ 

NH    CH2(OH).CH2— N 
CH2OH     CH2NH2  CH2NH2     CH2(OH).CH2/  CH2(OH).CH2/ 

Glycol.      Oxyethyl-    Dlinethylene  Dioxyethyl  Trioxyethyl 

amine.          dlainine.  ainine.  aniine. 

Aldehyde-ammonia  (p.  319),  a  crystalline  solid  formed  by  the  ac- 
tion of  dry  NH3  on  acetic  aldehyde:  CH3.CHO+NH3=CH3.CH<^ 
may  be  considered  as  ethidene  hydroxylamine  in  which  both  OH 
and  NH2  are  attached  to  the  same  carbon  atoms. 

Choline — TrimethyloxetJiylammonium  hydroxide  —  Bilineurine — 
CH2OH  OH 

^^         — occurs  in  hops,   in  fungi,   in  certain   seeds,   in  the 
CH2.N=(CH8)3  . 

human  placenta,  in  bile,  in  the  yolks  of  eggs,  and  in  the  cerebro-spmal 
fluid  in  epilepsy  and  other  organic  diseases  of  the  nervous  system. 
It  is  a  constituent  of  the  lecithins.  It  is  formed  synthetically  (as  its 
chloride)  by  the  union  of  ethylene  chlorhydrine  and  trimethylamine: 

CH2OH  CH2OH    Cl 

4-    N(CH8)8    =      |  / 

OH2C1  CH2-N=(CH8), 

It  is  produced  during  the  first  forty-eight  hours  of  putrefaction  of 
animal  tissues,  from  the  decomposition  of  the  lecithins,  and  diminishes 
from  the  third  day,  when  other  ptomaines  (neuridine,  putrescine, 
cadaverine)  increase  in  amount.  When  heated,  it  splits  up  into  glycol 
and  trimethylamine.  Nitric  acid  converts  it  into  muscarine. 

It  is  a  thick  syrup,  soluble  in  H20  and  in  alcohol,  and  strongly 
alkaline  in  reaction.  Even  in  dilute  aqueous  solution  it  prevents  the 
coagulation  of  albumin  and  redissolves  coagulated  albumin  and 
fibrin.  It  is  a  strong  base;  attracts  C02  from  the  air;  forms  with 
HC1  a  salt,  soluble  in  alcohol,  which  crystallizes  in  plates  and  needles, 
resembling  those  of  cholesterin.  Its  chloroplatinate  is  purified  with 
difficulty;  its  chloroaurate  readily.  It  is  poisonous  only  in  large 
doses. 

Amanitine — Trimethyloxethylideneammonium  hydroxide — Isocho- 

C*  TT  OTT 

/  —is  an  isomere  of  choline,  existing  along  with 

CHOH.N=(CH8), 


OXYAMINES  AND  DIAMINES  297 

muscarine  in  Agaricus  muscarius.  It  is  produced  by  methylation  of 
aldehydeammonia :  CH3.CHOH.NH2.  By  oxidation  with  HN03  it 
yields  muscarine. 

CH2OH        OH 
Muscarine. —  I  /          — is  related  to  choline,  neurine  and 

CHOH.N~(CH3)8 

amanitine  from  which  it  may  be  obtained  by  oxidation. 

It  occurs  in  nature  in  Agaricus  muscarius,  and  is  produced  dur- 
ing putrefactive  decomposition  of  proteins. 

The  free  base  occurs  in  very  deliquescent,  irregular  crystals,  or,  if 
not  perfectly  dry,  a  colorless,  odorless,  and  tasteless,  but  strongly 
alkaline  syrup;  readily  soluble  in  all  proportions  in  water  and  in 
alcohol ;  very  sparingly  soluble  in  chloroform ;  insoluble  in  ether.  It 
is  a  more  powerful  base  than  ammonium  hydroxide.  When  decom- 
posed it  yields  trimethylamine.  Its  chloroplatinate  crystallizes  in 
octahedra.  Its  chloride  forms  colorless,  brilliant,  deliquescent 
needles. 

When  administered  to  animals,  muscarine  causes  increased  secre- 
tion of  saliva  and  tears ;  vomiting ;  evacuation  of  f eces,  at  first  solid, 
later  liquid;  contraction  of  the  pupils,  almost  to  the  extent  of 
closure;  diminution  of  the  rapidity  of  the  pulse;  interference  with 
respiration  and  locomotion ;  gradual  sinking  of  the  heart 's  action  and 
respiration;  and  death.  Atropine  prevents  the  action  of  muscarine 
and  diminishes  its  intensity  when  already  established. 

CHa        OH 

Neurine — Trimetliylvinylammonium  hydroxide — 1 1       /  — is 

CH.N  =  (CH3)8 

a  base  resembling  choline,  for  which  reason  it  is  considered  here,  al- 
though its  proper  place  is  as  a  derivative  of  vinylamine.  It  has  been 
obtained  from  brain  tissue  and  from  the  suprarenal  capsule,  prob- 
ably as  a  product  of  decomposition  of  protagon.  It  is  produced  from 
choline  by  boiling  with  baryta  water.  The  same  body  is  one  of  the 
alkaloids  produced  by  the  putrefaction  of  muscular  tissue,  and  is 
endowed  with  poisonous  qualities,  resembling,  but  less  intense  than, 
those  of  muscarine. 

Betaines — are  lactams   (p.  323)  of  hypothetical  substances,  such 

CH2OH 
as  that  which  would  be  derived  from  choline :  I        /OH      by  oxida- 

6l2.N=(CH8)8 
COOH 

tion  of  the  methoxyl  group  to  a  carboxyl:  I        /OH      .     Although 

CH2.N  =(  CH3 )  3 

this  substance,  containing  both  carboxyl  and  basic  hydroxyl,  is  un- 
known, the  corresponding  betaine  aldehyde  and  chloride  are  known 
(see  formulae  below). 

COOH     OH 
The  betaines  have  the  general  formula:    |          /      ,  in  which  R" 

R"— N  = 

may  be  any  bivalent  hydrocarbon  radical,  and  in  which  the  three 


298 


TEXT-BOOK   OF   CHEMISTRY 


remaining  nitrogen  valences  may  be  satisfied  by  univalent  radicals 
or  by  a  trivalent  radical.  Or  the  arrangement  of  the  valences  may 

be  reversed,  as  in  nicotic-methyl  beta'ine:      I 

(C5H4)"'  =  N— CH8. 
Betaine — Trimefhyl-acetic   betaine  —  Oxyneurine  —  Oxycholine— 

COO 

TrimetJiyl-glycocoll —  I    \    _  — was  first  obtained  from  beet- 

juice  (Beta  vulgaris).  It  exists  in  beet-sugar  molasses,  in  cotton- 
seed, and  in  malt.  It  is  formed  by  several  synthetic  methods,  e.g., 
by  the  action  of  methyl  iodide  upon  amido-acetic  acid  (p.  323)  : 
COOH  COO 

-f  3CH8I=3HI+  I     \  ;  or  by  the  interaction  of  mono- 

CH2.NH8  CH2— N  ~  ( CH3 )  8. 

chloracetic  acid  and  trimethylamine : 

COOH  COO 

I         +N(CH3)3=         |     \  +HC1 

CH2C1  CH2— N=(CH3)3 

Betaine  crystallizes  in  large,  deliquescent  crystals,  with  one  mole- 
cule of  water  of  crystallization,  very  soluble  in  water  and  in  alcohol. 
It  is  decomposed  by  heat  with  evolution  of  trimethylamine,  a  fact 
which  is  utilized  to  obtain  that  substance  from  beet-molasses.  It  is 
strongly  basic  and  forms  crystalline  salts.  Its  chloraurate  is  crys- 
talline and  very  sparingly  soluble  in  cold  water. 

The  relations  of  the  oxyamine  bases  are  shown  in  the  following 
formulae : 


CH, 
CH, 


CH2OH 


CH, 


CH, 


C 


HOH 


CH2OH 
CHOH 


(CH3)8OH 

Ethyl-trlmethyl 
ammonium 
hydroxide. 

COH 


(CH8)8OH 

Choline. 


COOH 


/STT 
V^JHj 


(CH8)8OH 

Betaine 
aldehyde. 


(CH8)8C1 

Betaine 
hydrochlorlde. 


(CH8)3OH 

Isochollne, 
(Amanltlne). 


COO, 
Oidj    1 

,// 

(CH8)8 
Betaine 


/// 

(CH8)8OH 

Muscarine. 


CH, 

CH 
Ji 


(CH3)8OH 
Neurlne. 


Diamines — are  primary,  secondary,  and  tertiary,  as  they  contain 
two  groups  NH2,  or  two  groups  NH,  or  two  N  atoms : 


Trlmethylene  dlamlne. 


\T  /CH2.CH2\  »T 
^\CH2.CH2/^ 

Dlethylene  dlamlne. 


/CH2.CH2\ 

N— CH2.CH2— N 

\CH2.CH2/ 

Trletbylene  dlamlne. 


OXYAMINES  AND  DIAMINES  299 

The  primary  diamines  only  are  acyclic  compounds.  They  have 
the  algebraic  formula:  N2CnH2n  +  *;  the  secondary,  N2CnH2n+2;  and 
the  tertiary,  N2CnH2n.  The  secondary  and  tertiary  diamines  are  not 
known  beyond  the  ethylene  compounds  and  are  cyclic  compounds 
(see  Piperazine). 

The  primary  diamines  are  obtained  (1)  by  the  reduction  of  the 
olefine  dicyanides.  Thus  ethylene  cyanide  yields  tetramethylene 
diamine : 

CN.CH2.CH2.CN+4H2=H2N.CH2.CH2.CH2.CH2.NH2 

(2)  As  hydrobromides,  by  heating  the  olefine  bromides  with  alco- 
holic ammonia  to  100°  under  pressure: 

BrCH2.CH2Br+2NH3=H3Br :  :N.CH2.CH2.N :  :H3Br 

(3)  By  reduction  of  the  dinitroparaffins : 
N02CH2.CH2N02+6H2=H2N.CH2.CH2.NH2+4H20 

(4)  By  elimination  of  C02  from  the  diamido  acids  by  bacterial 
action. 

Alkyls  or  acidyls  may  be  substituted  for  H  in  NH2  of  the  diamines, 
as  in  the  monamines  (p.  294).  The  formation  of  their  dibenzoyl 
derivatives:  (C6H5.CO).HN.(CH2)4.NH.(CO.C6H5)  by  the  action 
upon  them  of  benzoyl  chloride  in  the  presence  of  NaOH  is  utilized 
for  their  identification  (see  pp.  225,  284).  Nitrous  acid  acts  upon 
them  as  upon  the  monamines  with  the  formation  of  glycols : 
H2N.CH2.CH2.NH2-j-2HN02=CH2OH.CH2.CH2CH2OH+2N2+2H20 
Among  the  diamines  are  included  several  of  the  products  of  putre- 
faction known  as  ptomaines. 

Ethylenediamine  —  H2N.(CH2)2.NH2  —  is  a  strongly  alkaline 
liquid,  boiling  at  116.5°.  With  acetyl  chloride  it  forms  diacetyl- 

CH2.NH.CO.CH3 
ethylene  diamine,    I  ,  which  is  decomposed  by  heat  with 

CH2.NH.CO.CH3 
formation  of  a  cyclic  amidine  base,   ethylene-ethenyl  amidine,   or 

CH2.NH . 

lysidine,   |  \  C.CH3. 

CH2.N     // 

Trimethylenediamine — H2N.(CH2)3.NH2 — is  said  to  have  been 
obtained  from  the  cultures  of  the  comma  bacillus.  It  has  been  ob- 
tained synthetically.  It  is  an  alkaline  liquid,  boiling  at  135  °. 

Tetramethylenediamine — Putrescine — H2N.  ( CH2)  4.NH2 — is  pro- 
duced along  with  cadaverine,  during  the  putrefaction  of  muscular 
tissue,  internal  organs  of  man  and  animals,  and  of  fish,  and  in  the 
culture  media  of  the  comma  bacillus  from  three  days  to  four  months. 
The  free  base  is  a  colorless  liquid  (solid  below  27°)  having  a  seminal 
odor,  which  absorbs  C02  from  the  air  and  unites  with  acids  to  form 
crystalline  salts.  It  is  not  actively  poisonous. 

Pentamethylenediamine — Cadaverine — H2N.  ( CH2)  5.NH2 — is  iso- 


300  TEXT-BOOK   OF    CHEMISTRY 

meric  with  neuridine  and  is  produced  during  the  later  stages  of  putre- 
faction of  many  animal  tissues,  the  choline  disappearing  as  this  and 
the  other  diamines  are  formed.  The  free  base  is  a  clear  syrupy  liquid, 
having  a  strong  disagreeable  odor,  resembling  that  of  coniine,  boils 
at  175  °,  and  fumes  in  air.  It  absorbs  C02  rapidly,  with  formation  of 
a  crystalline  carbonate.  Its  salts  are  crystalline.  The  chloride  on 
dry  distillation  is  decomposed  into  ammonium  chloride  and  piperidine. 

Neuridine  —  CgHj^N-j  —  a  diamine  of  undetermined  constitution, 
isomeric  with  cadaverine,  is  produced,  along  with  choline,  during 
the  earlier  stages  of  putrefaction,  particularly  of  gelatinoid  sub- 
stances, and  increases  in  quantity  as  putrefaction  advances,  while  the 
quantity  of  choline  diminishes.  The  free  base  is  a  gelatinous  sub- 
stance, having  a  very  marked  seminal  odor,  readily  soluble  in 
water,  insoluble  in  alcohol  and  in  ether.  Its  chloride  is  crystalline 
and  very  soluble  in  water.  It  seems  to  be  non-poisonous  when 
pure. 

Saprine  —  C4H16N2  —  another  diamine  of  undetermined  constitu- 
tion has  been  obtained  from  putrid  spleens  and  livers  after  three 
weeks'  putrefaction. 

Mydaleine  is  still  another  putrid  product  of  undetermined  com- 
position, but  probably  a  diamine  containing  four  or  five  carbon 
atoms,  which  forms  a  difficultly  crystallizable,  hygroscopic  chloride, 
which  is  actively  poisonous.  Five  milligrams  administered  hypo- 
dermically  to  a  cat  causes  death  after  profuse  diarrhea  and  secretion 
of  saliva,  violent  convulsions,  and  paralysis,  beginning  with  the  ex- 
tremities and  extending  to  the  muscles  of  respiration. 

AMIDINES—  AMIDOXIME&—  HYDROXAMIC  ACIDS. 

The  amidines  contain  both  the  amido  group,  NH2,  and  the  imido 
group,  NH,  and  have  the  general  formula:  RC^gz,  in  which  R  is 
any  univalent  hydrocarbon  radical. 

They  are  formed  by  heating  the  nitriles  (p.  305)  with  ammonium 
chloride.  Thus  acetonitrile  yields  acetamidine: 

CH3.C.:N+NH4C1=HC1+CH3.C/£|' 

They  are  also  formed  by  action  of  HC1  upon  the  amides.  Indeed, 
they  may  be  considered  as  being  derived  from  the  amides  (p.  310) 
by  substitution  of  NH  for  the  carbonyl  oxygen: 

+CH3.COOH 


(CH3.C/^H'=acetamide;  CH3.C  /****'  =acetamidine.)     The  amidines 
are  monacid  bases,  very  unstable  when  free. 

The  amidoximes  are  derived  from  the  amidines  by  substitution  of 
OH  for  hydrogen,  e.g.,  CH3.C/^2ppethenylamidoxime.     They  are 


GUANIDINE  AND  ITS  DERIVATIVES  301 

very  unstable  compounds,  formed  by  the  action  of  hydroxylamine 
upon  nitriles  or  upon  amidines. 

Hydroxamic  acids  contain  the  oxime  group,  N.OH,  while  the 
amido  group  of  the  amidine  is  replaced  by  hydroxyl:  CH3.C^^H 
acetohydroxamic  acid. 

GUANIDINE  AND  ITS  DERIVATIVES. 

Guanidine  —  Carbotriamine  —  CH5N3  —  was  first  obtained  by  oxida- 
tion of  guanine.  It  is  formed  (1)  by  heating  ethyl  orthocarbonate 
with  ammonia  : 

C(OC2H5)4+3NH3=HN:C:(NH2)2+4CH3.CH2OH 

(2)  From  cyanogen  iodide  and  ammonia: 

CNI-f  2NH3=HN  :C  :  (NH2)  2+HI 

(3)  As  hydrochloride  from  cyanamide  and  ammonium  chloride: 

CN.NH2+NH4C1=C1H2.:N  :C  :  (NH2)  2 

Substituted  guanidines  may  be  obtained  by  method  (3)  by  using 
hydrochlorides  of  primary  amines: 


Guanidine,  containing  the  group  -Cg2,  is  an  amidine.  It  may 
also  be  considered  as  a  triamine,  derived  from  three  ammonia  mole- 
cules, H2N  —  Cvf^H2-  ^  *s  related.  to  amidocarbonic  acid,  to  urea  and 
to  pseudourea,  as  is  indicated  by  the  formulae  : 


NH_C/NH2        0_C/NH2       NH 

"  C\NH2  \OH  -\OH 


Guanidine.  Urea.  Pseudourea.  Amido  carbonic 

acid. 

It  is  a  crystalline  solid,  which  absorbs  C02  and  H20  from  the  air, 
and  forms  crystalline  salts. 

Methyl-guanidine  —  Methyluramine  —  HN  :C  (NH2)  NH  (  CH3)  - 
was  first  obtained  by  the  oxidation  of  creatine  and  of  creatinine  (see 
below).  It  has  also  been  obtained  as  a  product  of  putrefaction  of 
muscular  tissue  at  a  low  temperature  in  closed  vessels,  when  it  prob- 
ably results  from  the  decomposition  of  creatine.  It  is  a  colorless, 
crystalline,  deliquescent,  strongly  alkaline  substance,  and  is  highly 
poisonous. 

The  relation  of  guanidine  and  methyl-guanidine  to  each  other  and 
to  creatine  and  creatinine  is  shown  by  the  following  formulae: 

HN_C/NH2  HN-C/NH* 

u  \NH2  u  \N  (  CH3  )  .CH2.COOH 

Guanidine.  Creatine. 

HN_r/NH2  /NH  -  CO 

U\NH(CH8)  HN=C  | 

\N(CH3)CH2 

Methyl-guanidine.  Creatinine. 


302  TEXT-BOOK   OF   CHEMISTRY 

Creatine  —  Methyl-guanidine  acetic  acid  —  C4H9N302+Aq  —  is,  as 
is  shown  by  the  above  graphic  formula,  a  complex  amido-acid.  It 
is  a  normal  constituent  of  the  juices  of  muscular  tissue,  brain,  blood, 
and  amniotic  fluid.  It  is  formed  synthetically  by  the  union  of 
methyl  glycocoll  and  cyanamide  : 


It  is  best  obtained  from  the  flesh  of  the  fowl,  which  contains  0.32 
per  cent.,  or  from  beef-heart,  which  contains  0.14  per  cent.  It  is 
soluble  in  boiling  H20  and  in  alcohol,  insoluble  in  ether  ;  crystallizes 
in  brilliant,  oblique,  rhombic  prisms;  neutral;  tasteless;  loses  Aq  at 
100°;  fuses  and  decomposes  at  higher  temperatures.  When  long 
heated  with  H20,  or  treated  with  concentrated  acids,  it  loses  H20, 
and  is  converted  into  creatinine.  Baryta  water  decomposes  it  into 
sarcosine  and  urea.  It  is  not  precipitated  by  silver  nitrate,  except 
when  it  is  in  excess  and  in  presence  of  a  small  quantity  of  potassium 
hydroxide.  The  white  precipitate  so  obtained  is  soluble  in  excess  of 
potash,  from  which  a  jelly  separates,  which  turns  black,  slowly  at 
ordinary  temperatures,  rapidly  at  100°.  A  white  precipitate, 
which  turns  black  when  heated,  is  also  formed  when  a  solution  of 
creatine  is  similarly  treated  with  mercuric  chloride  and  potash. 

Creatinine  —  Methyl-guanidine  acetic  lactam  —  C4H7N30  —  113  —  a 
product  of  the  dehydration  of  creatine,  is  a  normal  and  constant  con- 
stituent of  the  urine  and  amniotic  fluid,  and  also  exists  in  the  blood 
and  muscular  tissue. 

It  crystallizes  in  oblique,  rhombic  prisms,  soluble  in  H20  and  in 
hot  alcohol,  insoluble  in  ether.  It  is  a  strong  base,  has  an  alkaline 
taste  and  reaction  ;  expels  NH3  from  the  ammoniacal  salts,  and  forms 
well-defined  salts,  among  which  is  the  double  chloride  of  zinc  and 
creatinine  (C4H7N30)2ZnCl2,  obtained  in  very  sparingly  soluble, 
oblique  prismatic  crystals,  when  alcoholic  solutions  of  creatinine  and 
zinc  chloride  are  mixed. 

HYDRAZINES—  HYDRAZIDES. 

The  hydrazines  are  derivatives  of  hydrazine  or  diamidogen, 
H2N.NH2  (p.  96),  by  substitution  of  aliphatic  or  aromatic  radicals, 
alcoholic,  phenolic  or  acid,  for  one  or  more  of  the  hydrogen  atoms  in 
the  same  way  as  the  amines  are  derived  from  ammonia.  There  are, 
therefore,  primary,  secondary,  tertiary  and  quaternary  hydrazines; 
and  they  may  be  symmetrical,  as  C2H5HN.NH.C2H5  and  C6H5.HN.- 
NH.C2H5,  or  unsymmetrical,  as  C0H5HN.NH2  and  (C2H5)2N.NH2. 
The  aliphatic  hydrazines  are  obtained  from  the  alkyl-ureas,  by  con- 
version into  nitroso-amines,  and  reduction.  Most  of  the  hydrazines, 
some  of  which  are  of  considerable  interest,  are  derivatives  of  phenyl- 
hydrazine,  C0H5HN.NH2,  and,  containing  a  cyclic  chain  C6H5.  These 


CYANOGEN  COMPOUNDS  303 

will  be  considered  among  the  aromatic  compounds.    The  hydrazides, 
corresponding  to  the  amides,  contain  acidyls. 

NITRILES— CYANOGEN   COMPOUNDS. 

These  substances  may  be  considered  either  as  compounds  of  the 
univalent  radical  cyanogen  (CN)',  or  as  paraffins,  CnH2n+2,  in  which 
three  atoms  of  hydrogen  have  been  replaced  by  the  trivalent  N"'  atom, 
hence  nitriles,  compounds  of  N  with  the  trivalent  radicals  CnEten-i. 

Hydrogen  Cyanide — Hydrocyanic  acid — Prussic  acid — Formo- 
nitrile — Cyanogen  hydride — HC.:N — exists  ready  formed  in  the  juice 
of  cassava,  and  is  formed  by  the  action  of  H20  upon  bitter  almonds, 
cherry-laurel  leaves,  and  other  vegetable  products  containing  amyg- 
dalin,  a  glucoside,  which  is  decomposed  into  glucose,  benzoic  aldehyde 
(p.  362),  and  hydrocyanic  acid,  when  warmed  with  water.  It  is  also 
formed  in  a  great  number  of  reactions:  by  the  passage  of  the 
electric  discharge  through  a  mixture  of  acetylene  and  nitrogen: 

HC;CH+N2=2HC:N 
By  the  action  of  chloroform  on  ammonia: 

NH3+CHC13=3HC1+HCN 

By  the  distillation  of,  or  the  action  of  HN03  upon,  many  organic 
substances;  by  the  decomposition  of  cyanides  (see  Nitriles,  below). 

It  is  always  prepared  by  the  decomposition  of  a  cyanide  or  a 
ferrocyanide,  usually  by  acting  upon  potassium  ferrocyanide  with 
dilute  sulphuric  acid,  and  distilling.  Its  preparation  in  the  pure 
form  is  an  operation  attended  with  the  most  serious  danger,  and 
should  only  be  attempted  by  those  well  trained  in  chemical  manipu- 
lation. For  medical  uses  a  very  dilute  acid  is  required;  the  acidum 
hydrocyanicum  dilutum  (U.  S.  P.)  contains,  if  freshly  and  properly 
prepared,  two  per  cent,  of  anhydrous  acid.  That  of  the  French 
Codex  is  much  stronger — ten  per  cent. 

The  pure  acid  is  a  colorless,  mobile  liquid,  has  a  penetrating  and 
characteristic  odor ;  sp.  gr.  0.7058  at  7  ° ;  crystallizes  at  — 15  ° ;  boils 
at  26.5°;  is  rapidly  decomposed  by  exposure  to  light.  The  dilute 
acid  of  the  U.  S.  P.  is  a  colorless  liquid,  having  the  odor  of  the  acid ; 
faintly  acid,  the  reddened  litmus  returning  to  blue  on  exposure  to 
air;  sp.  gr.  0.997;  10  grams  of  the  acid  should  react  without  excess 
with  1.27  gram  of  silver  nitrate.  The  dilute  acid  deteriorates  on 
exposure  to  light,  although  more  slowly  than  the  concentrated;  a 
trace  of  phosphoric  acid  added  to  the  solution  retards  the  decom- 
position. 

Most  strong  acids  decompose  HCN.  The  alkalies  enter  into  double 
decomposition  with  it  to  form  cyanides.  It  is  decomposed  by  Cl  and 
Br,  with  formation  of  cyanogen  chloride  or  bromide.  Nascent  H 
converts  it  into  methylamine. 


304  TEXT-BOOK   OF   CHEMISTRY 

Analytical  Characters. —  (1)  With  silver  nitrate:  a  dense,  white 
ppt. ;  which  is  not  dissolved  on  addition  of  HN03  to  the  liquid,  but 
dissolves  when  separated  and  heated  with  concentrated  HN03 ;  soluble 
in  solutions  of  alkaline  cyanides  or  thiosulphates.  (2)  Treated  with 
NH4HS,  evaporated  to  dryness,  and  ferric  chloride  added  to  the  resi- 
due: a  blood-red  color,  which  is  discharged  by  mercuric  chloride. 
(3)  With  potash  and  then  a  mixture  of  ferrous  and  ferric  sulphates: 
a  greenish  ppt.,  which  is  partly  dissolved  by  HC1,  leaving  a  pure 
dark-blue  precipitate.  (4)  Heated  with  a  dilute  solution  of  picric 
acid  and  then  cooled:  a  deep-red  color.  (5)  Moisten  a  piece  of 
filter-paper  with  a  freshly  prepared  alcoholic  solution  of  guaiac ;  dip 
the  paper  into  a  very  dilute  solution  of  CuS04,  and,  after  drying, 
into  the  liquid  to  be  tested.  In  the  presence  of  HCN  it  assumes  a 
deep-blue  color.  (6)  Add  a  few  drops  of  potassium  nitrite  solution, 
then  two  or  three  drops  of  ferric  chloride  solution,  and  enough  dilute 
H2S04  to  turn  the  color  to  yellow.  Heat  just  to  boiling;  cool,  add 
a  few  drops  of  NH4OH,  filter,  and  add  to  the  filtrate  a  few  drops 
of  dilute,  colorless  ammonium  sulphydrate:  a  violet  color,  changing 
to  blue,  then  to  green  and  yellow. 

Toxicology. — Hydrocyanic  acid  is  a  violent  poison,  whether  it  is  inhaled 
as  vapor,  or  swallowed,  either  in  the  form  of  dilute  acid,  of  soluble  cyanide, 
or  of  the  pharmaceutical  preparations  containing  it,  such  as  oil  of  bitter  almonds 
and  cherry-laurel  water;  its  action  being  more  rapid  when  taken  by  inhalation 
or  in  aqueous  solution  than  in  other  forms.  When  the  medicinal  acid  is  taken 
in  poisonous  dose,  its  lethal  effect  may  seem  to  be  produced  instantaneously; 
nevertheless,  several  respiratory  efforts  usually  are  made  after  the  victim  seems 
to  be  dead,  and  instances  are  not  wanting  in  which  there  was  time  for  con- 
siderable voluntary  motion  between  the  time  of  ingestion  of  the  poison  and 
unconsciousness.  In  the  great  majority  of  cases  the  patient  is  either  dead  or 
fully  under  the  influence  of  the  poison  on  the  arrival  of  the  physician,  who 
should,  however,  not  neglect  to  apply  the  proper  remedies  if  the  faintest  spark 
of  life  remains.  Chemical  antidotes  are,  owing  to  the  rapidity  of  action  of  the 
poison,  of  no  avail,  although  possibly  chlorine,  recommended  as  an  antidote  by 
many,  may  have  a  chemical  action  on  that  portion  of  the  acid  already  ab- 
sorbed. The  treatment  indicated  is  directed  to  the  maintenance  of  respira- 
tion; cold  douche,  galvanism,  artificial  respiration,  until  elimination  has  re- 
moved the  poison.  If  the  patient  survives  an  hour  after  taking  the  poison, 
the  prognosis  becomes  very  favorable;  in  the  first  stages  it  is  exceedingly  un- 
favorable, unless  the  quantity  taken  has  been  very  small. 

In  cases  of  suspected  homicide  by  hydrocyanic  acid,  the  stomach  should 
never  be  opened  until  immediately  before  the  analysis. 

Cyanogen  Chlorides. — Two  polymeric  chlorides  are  known: 
Cyanogen  chloride,  CNC1,  formed  by  the  action  of  Cl  upon  anhydrous 
HCN  or  upon  Hg(CN)2  in  the  dark.  It  is  a  colorless  gas,  condensing 
to  a  liquid  at  15  ° ;  intensely  irritating  and  poisonous.  Tricyanogen 
chloride,  C3N3C13,  is  formed,  as  a  crystalline  solid,  when  anhydrous 
HCN  is  acted  upon  by  Cl  in  sunlight.  It  fuses  at  146°.  (See 
Cyanidine,  p.  414.) 


CYANOGEN  COMPOUNDS  305 

Cyanides. — The  most  important  of  the  simple  metallic  cyanides 
are  those  of  K  and  Ag. 

Nitriles. — The  hydrocyanic  esters  of  the  univalent  alcoholic  radi- 
cals are  called  acid  nitriles,  because  of  their  formation  from  the 
amides,  by  the  reaction  given  under  (3)  below.  Hydrocyanic  acid, 
being  produced  from  f ormamide,  is  formonitrile ;  methyl  cyanide,  de- 
rived from  acetamide,  is  acetonitrile,  etc.  They  are  also  derivable 
from  the  ammonium  salt  of  the  acid  by  elimination  of  the  elements 
of  two  molecules  of  water.  Their  formulae  may  be  derived  from  those 
of  the  acids  by  substitution  of  N  for  the  trivalent  OOH  of  the  car- 
boxyl.  The  acid  nitriles  are  not  to  be  confounded  with  the  acidyl 
cyanides,  which  are  the  nitriles  of  the  ketonic  acids. 

The  nitriles  are  produced:  (1)  By  heating  the  haloid  esters  (p. 
205)  with  alcoholic  solution  of  potassium  cyanide  at  100°: 

CH3.CH2I+KCN=CH3.CH2.CN+KI 

(2)  By  distilling  a  mixture  of  potassium  cyanide  and  the  potas- 
sium salt  of  a  monoalkyl  sulphate.    Thus,  ethyl  cyanide  is  produced 
from  potassium  ethylsulphate : 

KCN+S04.C2H5.K=K2S04+C2H5.CN 

(3)  By  complete   dehydration,   by   the   action  of   P205,    of   the 
ammoniacal  salt  of  the  acid,  or  of  its  amide.     Thus  acetonitrile  is 
obtained  from  ammonium  acetate: 

CH3COO  (NH4)  =CH3.CN+2H20 
or  from  acetamide : 

CH3.CO.NH2=CH3.CN+H20 

(4)  By  the  action  of  acidyl  chlorides  upon  silver  cyanate.    Thus, 
with  acetyl  chloride,  methyl  cyanide  is  formed: 

CNOAg+CH3.CO.Cl=rAgCl+C02+CH3.CN 

The  formation  of  the  nitriles  is  frequently  utilized  to  pass  from 
a  given  carbon  compound  to  its  next  superior  homologue.  Thus 
ethyl  alcohol  may  be  obtained  from  methyl  alcohol  by  the  steps: 

H.CH2OH    — >     CH3.I    — >     CH3.CN    -^>     CH3.COOH    — > 
CH3.CHO    — >CH3.CH2OH   (Seep.  251). 

The  nitriles  combine  with  nascent  hydrogen  to  form  primary 
amines.  Thus  acetonitrile  forms  ethylamine: 

CH3.CN+2H2=C2H5.NH2 

Hydrating  agents  convert  them  into  the  ammonium  salts  of  the  cor- 
responding acids.  Thus  ammonium  propionate  is  derived  from  ethyl 
cyanide:  C2H,.CN+2H,0=C2H5.COO(NH4).  Or,  when  acted  upon 
by  concentrated  sulphuric  acid,  hydrogen  peroxide,  or  concentrated 
hydrochloric  acid,  they  take  up  one  molecule  of  water  and  form 


306  TEXT-BOOK   OF   CHEMISTRY 

amides.       Thus     acetonitrile     forms     acetamide:     CH3.CN-f-H20= 
CH3.CO.NH2. 

Methyl  Cyanide — Acetonitrile — CH3.CN — is  a  colorless  liquid, 
b.  p.  81.6°,  having  an  agreeable  odor,  sparingly  soluble  in  water, 
obtained  by  distilling  ammonium  acetate  or  acetamide  with  P205. 

The  isocyanides,  carbylamines,  or  carbamines,  are  isomeres  of  the 
nitriles,  which  differ  from  the  latter  in  constitution  in  that,  in  the 
nitriles,  the  nitrogen  is  trivalent,  and  the  alkyl  group  is  in  union  with 
carbon,  e.g.,  methyl  cyanide,  N=C — CH3,  while  in  the  carbylamines 
the  nitrogen  is  quinquivalent,  and  the  alkyl  is  in  union  with  nitrogen, 
e.g.,  methyl  isocyanide,  C  =  N — CH3.  The  difference  in  constitution 
between  the  nitriles  (alkyl  cyanides)  and  the  alkyl  isocyanides  is 
shown  by  the  difference  in  their  behavior  with  hydrating  agents. 
While  the  cyanides  yield  the  ammonium  salts  of  the  corresponding 
acids : 

CH3.CH2.CN+2H20=CH3.CH2.COO(NH4) 

the  isocyanides  are  split  into  a  primary  amine  and  formic  acid: 
CH3.CH2.NC+2H20=CH3.CH2.NH2+H.COOH 

The  alkyl  magnesium  halides  act  differently  upon  cyanides  and 
isocyanides.  With  the  former  an  addition  product  is  formed  accord- 
ing to  the  equation : 

R.Mg.X+R'.CN=RR'  :C  :N.MgX, 
which  when  hydrolyzed  produces  ketones: 

RR'  :C  :N.MgX+2H20=R.CO.R'+NH3+HOMgX 

With  the  isocyanides  the  addition  is : 

R'.N=C+RMgX=R'N  :C  <^gX 
which  when  hydrolyzed  produces  imines : 

R'N  :C  <^gX  +H20=R'N  :CH.R+HO.MgX 

The  isocyanides  are  formed:  (1)  by  the  action  of  a  primary  mon- 
amine  on  chloroform  in  the  presence  of  caustic  potash.  Thus  methyl 
isocyanide  is  derived  from  methylamine: 

CH3.NH2+CHC13=3HC1+CN.CH3 

(2)  By  the  action  of  alkyl  iodides  upon  silver  cyanide: 
CH3I+AgCN=AgI+CN.CH3 

Methyl  Isocyanide — Methylcarbylamine — Isoacetonitrile  —  CH3.- 
NC — is  a  colorless  liquid,  b.  p.,  58°,  having  a  disagreeable  odor,  and 
giving  off  highly  poisonous  vapor.  It  is  formed  by  the  reactions 
given  above,  and  is  said  to  exist  in  the  venom  of  toads. 

Phenyl  Isocyanide — Isobenzonitrile — C6H5.NC — is  a  colorless 
liquid,  not  boiling  without  decomposition,  having  an  intensely  dis- 
agreeable odor,  whose  formation  is  utilized  in  a  test  for  chloroform. 

Both  nitriles  and  isonitriles  combine  with  the  hydracids  to  form 


CYANOGEN  COMPOUNDS  307 

crystallite  salts,  decomposable  by  water;  the  latter  much  more  en- 
ergetically than  the  former.  They  are  all  volatile  liquids ;  the  nitriles 
having  ethereal  odors  when  pure,  the  isonitriles  odors  which  are  very 
powerful  and  disagreeable. 

Dicyanogen — CN.CN — is  prepared  by  heating  mercuric  cyanide, 
and  is  also  formed  by  passing  an  electric  arc  between  carbon  points 
in  an  atmosphere  of  nitrogen. 

It  is  a  colorless  gas,  has  a  pronounced  odor  of  bitter  almonds: 
sp.  gr.,  1.8064  A.  It  burns  in  air  with  a  purple  flame,  giving  off  N 
and  C02.  It  is  quite  soluble  in  water,  but  the  solutions  soon  turn 
brown,  and  then  contain  ammonium  oxalate  and  formate,  urea,  and 
hydrocyanic  acid. 

Nitriles  of  Carbonic  and  Thiocarbonic  Acids. — These  constitute 
the  oxygen  and  sulphur  compounds  of  cyanogen.  Thus  cyanic  acid 
is  the  nitrile  of  carbonic  acid:  C03H(NH4)=CONH+2H20,  and 
thiocyanic  acid  that  of  thiocarbonic  acid:  C02SH(NH4)=CSNH+ 
2H20. 

Three  structural  formula  of  these  compounds  are  possible:  N=C.- 
OH,  0=C=N.H,  and  CEEN.OH.  The  first  structure  is  that  of  the 
normal  cyanic  and  thiocyanic  acids,  the  second  that  of  the  isocyanates 
and  isothiocyanates,  the  third  that  of  fulminic  acid. 

Cyanic  Acid — NC.OH — is  obtained  by  distillation  of  cyanuric 
acid,  or,  in  its  salts,  by  calcining  the  cyanides  in  presence  of  an  oxi- 
dizing agent,  or  by  the  action  of  dicyanogen  upon  solutions  of  the 
alkalies  or  alkaline  carbonates. 

It  is  a  colorless  liquid,  only  stable  below  0°;  has  a  strong  odor, 
resembling  that  of  formic  acid ;  and  is  soluble  in  water ;  gives  off  an 
irritating  vapor ;  is  vesicating  to  the  skin ;  and  is  changed  by  exposure 
to  air  into  its  polymere,  cyamelide,  a  white,  porcelain-like  solid. 

Cyanuric       Acid  —  Tricyanic       acid  —  Trioxycyamdine  —  HO.- 

C  \2fcC(OH)/N — is  produced  by  dry  distillation  of  uric  acid;  by 
the  action  of  heat  or  of  Cl  upon  urea ;  by  heating  tricyanogen  chloride 
or  bromide  with  water  or  with  alkalies.  It  forms  colorless  crystals, 
odorless,  almost  tasteless,  feebly  acid,  rather  soluble  in  water.  It  is 
tribasic.  It  may  be  dissolved  in  strong  H2S04  ox  HN03  without  de- 
composition, but,  when  boiled  with  acids  or  alkalies,  it  is  decomposed 
into  carbon  dioxide  and  ammonia;  and,  when  distilled,  into  cyanic 
acid. 

The  ordinary  potassium  and  ammonium  cyanates  are  regarded  as 
isocyanates,  salts  of  isocyanic  acid,  or  carbimide,  0 :  C :  NH.  The 
ammonium  salt,  0:C:N(NH4),  is  converted  into  its  isomere,  urea, 
H2N.CO.NH2,  by  evaporation  of  its  solution.  The  isocyanic  esters 
serve  for  the  generation  of  the  alkyl  ureas. 

Fulminic  Acid — Carbyloxime — CEEN.OH — is  a  strongly  acid  sub- 
stance, having  the  odor  and  poisonous  qualities  of  hydrocyanic  acid, 


308  TEXT-BOOK   OF   CHEMISTRY 

whose  Ag  and  Hg  salts  are  formed  by  the  action  of  nitrous  acid  upon 
alcohol  and  silver,  or  mercuric,  nitrate.  Mercuric  fulminate,  or 
fulminating  mercury,  crystallizes  in  white,  soluble  needles,  and  ex- 
plodes violently  upon  shock.  It  is  used  in  percussion  caps,  primers 
and  cartridges.  Silver  fulminate  is  more  violently  explosive  than 
the  mercurial  salt.  Fulminating  gold  is  not  a  fulminate,  but  auro- 
amidoimide,  Au(NH)NH2+3H20. 

Fulminuric  Acid  —  CN.CH(N02).C  \^K  —  metameric  with  cyan- 
uric,  and  polymeric  with  cyanic  and  isocyanic  acids,  is  a  deriva- 
tive of  tartronic  acid,  COOH.CHOH.COOH  ;  whose  alkali  salts  are 
formed  by  boiling  solutions  of  alkaline  chlorides  with  mercuric 
fulminate. 

Thiocyanic  Acid  —  Sulphocyanic  acid  —  Cyanogen  sulphydrate— 
N=C.SH  —  is  obtained  by  decomposition  of  its  salts,  which  are  formed 
by  boiling  solutions  of  the  cyanides  with  sulphur;  by  the  action  of 
dicyanogen  upon  the  metallic  sulphides  ;  and  in  several  other  ways. 

The  free  acid  is  a  colorless  liquid,  crystallizes  at  —  12.5°,  acid  in 
reaction.  The  prominent  reaction  of  the  acid  and  of  its  salts  is  the 
formation  of  a  deep-red  color  with  the  ferric  salts;  the  color  being 
discharged  by  mercuric  chloride  -  solution. 

Thiocyanates  exist  in  the  human  saliva  and  in  the  stomach-con- 
tents, in  small  amount.  The  free  acid  is  poisonous. 

Isothiocyanic  Esters  —  Mustard  oils  —  Isothiocyanic  acid,  S  :C  :- 
NH,  is  not  known  in  the  free  state.  Its  esters  are  called  mustard 
oils,  from  the  most  important  of  the  class,  allyl  isothiocyanate,  which 
is  the  essential  oil  of  mustard. 

The  mustard  oils  are  obtained:  (1)  by  mixing  ether  solutions  of 
primary  amines  and  carbon  disulphide,  and  evaporating  the  solu- 
tions, the  amine  salts  of  alkyl  dithiocarbamic  acids  are  formed: 

CS2+2C2H6.NH2=SC 


On  boiling  aqueous  solutions  of  these  with  AgN03,  FeCl3  or  HgCl2, 
the  metallic  sulphides  are  precipitated,  and  hydrogen,  sulphide  and 
the  mustard  oils  are  formed,  the  latter  distilling  over.  The  reaction 
takes  place  in  two  stages: 


sr/NH.CaH5  A  N0  9r/NH.CaH6     ,      N0  N  ^H»         and 

U  \  S  (  NH3.C2H6  )  AgN°3  C  \  SAg  \  C2HB  »  8 

Ethylammonium  Silver  Silver  Etliylnnnnoniuni 

ethylthiocarbamate.  nitrate.  ethyldithiocarbamate.  nitrate. 

+     H'S     +     2SC:N.C1H. 

Ethyl  iaocyunate. 

Hoffman's  test  for  the  primary  amines  (p.  295)  is  based  upon 
these  reactions. 

The  mustard  oils  are  liquids,  insoluble  in  water,  giving  off  vapors 
of  penetrating  odor  and  irritating  to  the  eyes.  When  heated  with 


CYANOGEN  COMPOUNDS  309 

water  under  pressure  to  200°,  or  with  hydrochloric  acid  to  100°, 
they  are  decomposed  into  carbon  dioxide,  hydrogen  sulphide  and 
amines : 

SC  :N.C2H5+2H20=C02+SH2+NH2.C2H5 

Heating  with  dilute  H2S04  decomposes  them  into  amines  and 
carbon  oxysulphide,  COS.  With  nascent  hydrogen  they  yield  thio- 
f ormaldehyde  and  a  primary  amine : 

SC  :N.C2H5+2H2=H.CSH+NH2.C2H5 

Heated  with  monocarboxylic  acids  they  form  carbon  oxysulphide, 
esters,  and  monamides: 

SC:N.C2H5+2CH3.COOH=COS+CH3.COO.C2H5+NH2.CH3.CO 

Their  alcoholic  solutions,  when  boiled  with  HgO,  yield  isocyanic 
esters,  which  are  converted  by  water  into  the  corresponding  com- 
pound ureas. 

Cyanamide — CN.NH2 — is  the  nitrile  of  carbamic  acid :  OC  :NH2.- 
O.NH4.— 2H20=CN.NH2.  It  is  formed  by  the  action  of  cyanogen 
chloride  upon  ammonia: 

CNC1+2NH3=NH4C1+CN.NH2 
or  by  the  action  of  thionyl  chloride  upon  urea : 

NH2.CO.NH2+SOC12=CN.NH2+S02+2HC1 

It  forms  colorless  crystals,  soluble  in  water,  alcohol  or  ether. 
Corresponding  to  it  are  substituted  cyanamides,  which  may  be  formed 
by  using  a  primary  amine  in  place  of  ammonia  in  the  above-men- 
tioned method  of  preparation: 

CNC1+2NH2.CH3=NH3.CH3.C1+CN.NHCH3 
Heated  with  ammonium  chloride  it  forms  guanidine  hydrochloride : 

CN.NH2+NH4C1=H3C1N.C  ^™ 
Hydrating  agents  convert  it  into  urea: 

CN.NH2+H20=rH2N.CO.NH2. 

Metallocyanides. — The  metallic  compounds  of  cyanogen,  the  cya- 
nides, may  be  divided  into  three  classes:  (1)  the  simple  cyanides,  such 
as  potassium,  silver,  or  mercuric  cyanide,  which  resemble  in  consti- 
tution and  general  characters  the  chlorides,  bromides,  and  iodides; 
(2)  the  double  cyanides,  such  as  AgK(CN)2,  or  HgK2(CN)4,  which 
are  constituted  like  other  double  salts.  These  salts  have  crystalline 
forms  and  solubilities  of  their  own,  independent  of  those  of  the  sim- 
ple cyanide  of  which  they  are  made  up.  They  are  readily  decomposed 
by  cold  acids,  with  liberation  of  hydrocyanic  acid;  (3)  compound 
cyanides,  or  metallocyanides,  in  which  the  cyanogen  groups  are  more 
intimately  attached  to  the  metal,  in  such  manner  that  the  ordinary 
analytical  characters  of  the  metals  are  completely  masked ;  and  when 


310  TEXT-BOOK   OF   CHEMISTRY 

they  are  decomposed  by  cold  acids  hydrocyanic  acid  is  not  liberated, 
but  a  complex  metallohydrocyanic  acid,  corresponding  in  constitution 
to  the  salt.  The  metals  entering  into  the  composition  of  the  metal- 
locyanides  are  iron  (ferro-  and  ferricyanides),  cobalt  (cobalticya- 
nides),  and  platinum  (platinocyanides) ;  also  chromium  and  manga- 
nese in  the  ic  form. 

The  metallocyanides  are  considered  as  derivatives  of  two  hypo- 
thetical acids,  polymeres  of  hydrocyanic  acid:  dihydrocyanic  acid 
and  trihydrocyanic  acid,  which,  in  the  hydrometallocyanic  acids  and 
their  salts,  are  combined  with  the  constituent  metal,  with  loss  of 
hydrogen,  as  shown  in  the  following  formulae: 

H— C=N  H— C=N C— H 

N=C— H  N=CH— N 

Dihydrocyanic  acid.  Trihydrocyanic  acid. 

_    //C3N3.K 

~   /C,N8.K,  *e\C3N3.K2  pt/C2N2.H 

Fe\C8Ns.Ka  Je//C3N8.K  Pt\C2N2.H 

e\C8N8.Ka 

Potassium  Potassium  Hydroplatlnocyanlc 

ferrocyanlde.  ferrlcyanlde  acid. 

Hydronitroprussic  Acid — Fe(CN)5(NO)H2 — contains  the  nitroso 
group  NO,  and  is  produced  when  potassium  ferrocyanide  is  acted 
upon  by  nitric  acid.  Its  sodium  salt,  sodium  nitroprusside,  is  formed 
by  neutralizing  the  acid  with  sodium  carbonate.  It  forms  brilliant 
red  prisms;  and  is  used  as  a  test  for  sulphides,  with  which  it  forms 
a  violet  color.  (See  test  No.  6,  Hydrocyanic  acid,  p.  304.) 

AMIDES. 

These  compounds  are  similar  in  constitution  to  the  amines 
(p.  292),  from  which  they  differ  in  that  the  radicals  substituted  in 
ammonia  are  acidyls  in  place  of  alkyls:  N^j£-CH' ;  N^caCH')2  ; 

N(CO.CH3)3. 

Like  the  amines  they  are  classified  into  monamides,  diamides  and 
triamides,  according  as  they  are  derived  from  one,  two,  or  three 
molecules  of  ammonia. 

Mixed  amides  are  also  known,  produced  by  the  substitution  of  acid 
radicals  for  the  remaining  hydrogen  of  the  primary  and  secondary 
amines,  e.g.,  diethyl  acetamide:  CH3CO(C2H5)2N. 

MONAMIDES— AMIC   ACIDS. 

Like  the  monamines,  the  monamides  are  primary,  secondary,  or 
tertiary,  as  they  contain  one,  two  or  three  substituted  radicals. 

The  primary  monamides  corresponding  to  the  monocarboxylic 
acids  may  also  be  considered  as  being  derived  from  those  acids  by 


AMIDES  311 

substitution  of  NH2  for  the  OH  of  the  group  COOH ;  as  the  amines 
are  derivable  from  the  alcohols  by  substitution  of  NH2  for  OH  in 
CH2OH,  CHOH  or  COH.  Thus  acetamide,  CH3.CO.NH2  is  derived 
from  acetic  acid,  CH3.CO.OH. 

The  primary  monamides  are  formed:  (1)  by  the  action  of  heat 
upon  the  ammonium  salt  of  the  acid,  with  elimination  of  the  ele- 
ments of  one  molecule  of  water : 

CH3.COO  (NH4)  =H20+CH3.CO.NH2 

It  will  be  remembered  that  the  nitriles  (p.  305)  are  derived  from 
the  ammoniacal  salts  by  elimination  of  two  molecules  of  water : 

CH3.COO  (NH4)  =2H20+CH3.CN 

(2)  By  addition  of  H20  to  the  nitriles.    Thus  hydrogen  peroxide 
in  alkaline  solution  converts  acetonitrile  into  acetamide: 

2CH3.CN+2H202=2CH3.CO.NH2+02 

(3)  By  the  action  of  ammonia  upon  esters.    Thus,  ethyl  acetate 
and  ammonia  produce  acetamide  and  ethylic  alcohol : 

CH3.COO(C2H5)+NH3=CH3.CO.NH2+CH3.CH2OH 

(4)  By  the  action  of  an  acidyl  chloride  upon  dry  ammonia.    Thus, 
acetamide  is  produced  by  acetyl  chloride : 

CH3.CO.C1+2NH3=NH4C1+CH3.CO.NH2 

The  secondary  monamides  are  obtained:  (1)  by  the  action  of 
acidyl  chlorides  upon  the  primary  monamides.  Thus,  diacetamide  is 
produced  from  monacetamide : 

CH3.CO.NH2+CH3.CO.C1=HC1+(CH3CO)2NH 

(2)  By  the  action  of  hydrochloric  acid  upon  the  primary  mon- 
amides at  high  temperatures: 

2(CH3.CO.NH2)+HC1=NH4C1+(CH3CO)2NH 

The  tertiary  amides  01  this  series  have  been  imperfectly  studied. 
Some  have  been  obtained  by  the  action  of  acidyl  chlorides  upon  me- 
tallic derivatives  of  secondary  amides: 

(CH3.CO)2NaN+CH3.CO.Cl=(CH3.CO)3N+NaCl 
or  by  the  union  of  anhydrides  and  nitriles  at  200  ° : 
CH3.CN+(CH3.CO)20=(CH3.CO)3N 

The  primary  monamides  of  the  fatty  acids  are  solid,  crystalliz- 
able,  neutral  in  reaction,  volatile  without  decomposition,  mostly  solu- 
ble in  alcohol  and  ether,  and  mostly  capable  of  uniting  with  acids  to 
form  compounds  similar  in  constitution  to  the  ammoniacal  salts: 

H2N.CO.CH3+HN03=(H3N.CO.CH3)N03 


312  TEXT-BOOK   OF   CHEMISTRY 

They  arc  capable  of  uniting  with  H20  to  form  the  ammoniacal 
salts  of  the  corresponding  acids : 

H2N.CO.CH3+H20=CH3.COO  (NH4) 

And  with  the  alkaline  hydroxides  to  form  the  metallic  salts  of  the 
corresponding  acids  and  ammonia: 

HaN.CO.CH3+KOH=CH3.COOK+NH3 

They  are  converted  into  amines  containing  one  atom  of  carbon 
less  than  themselves  by  the  action  of  bromine  and  alkali.  The  sec- 
ondary monamides,  containing  two  radicals  of  the  tatty  series,  are 
acid  in  reaction,  and  their  remaining  atom  of  extra-radical  hydrogen 
may  be  replaced  by  an  electro-positive  atom. 

The  action  of  bromine  on  the  amides  in  alkaline  solution,  results 
in  the  formation  of  amines  containing  one  atom  of  carbon  less. 
The  reaction  takes  place  in  two  stages,  with  intermediate  formation 
of  a  bromamide: 

(CH3.CO).NH2+Br2+KOH=(CH3.CO)NHBr+KBr+H20,  and 
(CH3.CO)NHBr+3KOHr=CH3.NH2+C03K2+KBr+H20 

As  the  amides  are  readily  obtained  by  dehydration  of  the  NH4 
salts  of  the  acids,  and  as  the  amines  yield  alcohols  which  may  in 
turn  be  oxidized  to  acids: 

CH3.NH2+HN02=H.CH2OH+N2+H20 

this  offers  a  means  of  "stepping  down." 

Formamide — CHO.NH2 — 45 — is  a  colorless  liquid,  soluble  in 
H20  and  in  alcohol,  boils  at  192°-195°,  suffering  partial  decomposi- 
tion, obtained  by  heating  ethyl  formate  with  an  alcoholic  solution  of 
ammonia,  or  by  the  dry  distillation  of  ammonium  formate.  It  is  de- 
composed by  dehydrating  agents,  with  formation  of  hydrocyanic 
acid:  H2N(H.CO)=rHCN+H20.  Mercury  formamide  is  obtained 
in  solution  by  gently  heating  freshly-precipitated  mercuric  oxide  with 
H20  and  formamide. 

Under  the  name  chloralamide  a  compound,  formed  by  the  union  of 
chloral  and  formamide,  and  having  the  constitution,  CCl3.CH(^g  CHO 

has  been  used  as  a  hypnotic.  It  forms  colorless,  odorless,  faintly 
bitter  crystals,  fusible  at  115°,  sparingly  soluble  in  water.  It  is 
decomposed  by  alkalies,  chloroform  and  ammonia  being  among  the 
products  of  the  decomposition.  It  is  not  affected  by  acids. 

Chloralimide — CCl3.C^gH — is  another  related  derivative,  formed 

by  the  action  of  ammonium  acetate  upon  chloral  hydrate,  or  by  heat- 
ing chloral  ammonia.  It  is  a  crystalline  solid,  sparingly  soluble  in 
water,  readily  soluble  in  ether  and  in  alcohol.  When  heated  to  180° 
it  is  decomposed  into  chloroform  and  formamide. 

Acetamide — CH3.CO.NH2 — is  obtained  by  heating,  under  pres- 


AMIDES   OF   DICARBOXYLIC   ACIDS  313 

sure,  a  mixture  of  ethyl  acetate  and  ammonium  hydroxide,  and  puri- 
fying by  distillation.  It  is  solid,  crystalline,  very  soluble  in  H20, 
alcohol,  and  ether  ;  fuses  at  82  °  ;  boils  at  222  °  ;  has  a  sweetish,  cooling 
taste,  and  an  odor  of  mice.  Boiling  potassium  hydroxide  solution 
decomposes  it  into  potassium  acetate  and  ammonia.  Phosphoric  an- 
hydride deprives  it  of  H20,  and  forms  with  it  acetonitrile  or  methyl 
cyanide:  H2N.CO.CH3=:CH3.CN+H20. 

AMIDES  OF  DICARBOXYLIC  ACIDS. 

As  the  hydramines,  the  diamines   (p.  296)   and  the  imines  are 

all  derivable   from   the   dihydric   alcohols,   by  substitution   of  NH2 

.for  OH  in  the  first,  of  2NH2  for  20H  in  the  second,  and  of  NH  for 

20H  in  the  last,  so  amic  acids,  diamides,  and  imides  are  correspond- 

ingly derived  from  the  dicarboxylic  acids: 

COOH  CONH2  CONH2  C0\ 

I  I  I  I         NH 

COOH  COOH  CONH2  CO/ 

Oxalic   acid.  Oxamic  acid.  Oxamide.  Oximide. 

and,  recognizing  that  carbonic  acid  is  a  pure  dicarboxylic  acid,  al- 
though not  a  member  of  the  oxalic  series,  we  have  : 

nn/OH  /NH2  /NH2  - 

C\OH 


Carbonic  acid.  Carbamic  acid.  Carbamide.  Carbimide. 

Amic  acids  are,  therefore,  acids  derived  from  two  carboxylic 
acid  groups  by  substituting  NH2  for  one  OH. 

Carbamic  Acid  —  Amidoformic  Acid  —  H2N.CO.OH  —  is  not  known 
in  the  free  state,  being  decomposed  into  C02  and  NH3,  but  ammonium 
carbamate  is  formed  whenever  ammonia  and  carbon  dioxide  are  in 
contact:  C02+2NH3=rH2N.CO.O(NH4),  and  it  therefore  exists  in 
commercial  ammonium  carbonate,  and  is  formed  by  oxidation  of  many 
carbon-nitrogen  compounds,  notably  amido-acids,  in  alkaline  solu- 
tion. It  exists  normally  in  the  blood  and  urine,  and  is  formed  in  the 
system  as  an  intermediate  product  between  amido-acids  and  urea.  It 
is  obtained  by  directing  dry  ammonia  and  carbon  dioxide  into  cold 
absolute  alcohol,  as  a  white  crystalline  precipitate. 

The  esters  of  carbamic  acid,  called  urethanes,  are  more  stable  than 
its  salts.  They  are  formed  by  the  action  of  ammonia  upon  the  car- 
bonic esters: 

OC  :  (OC2H5)  2+NH3=H2N.CO.O  (  C2H5)  +CH3.CH2OH 
and  by  the  action  of  cyanogen  chloride  upon  alcohols  : 

CNC1+2CH3.CH2OH=H2N.CO.O(C2H5)+CH3.CH2C1 

Ethyl  urethane,  produced  by  the  above  reactions,  forms  thin, 
large,  transparent  plates,  f.  p.  50°,  b.  p.  184°,  very  soluble  in  water 


314  TEXT-BOOK   OF   CHEMISTRY 

and  in  alcohol.  It  is  used  as  a  hypnotic,  either  alone  or  combined  with 
chloral  in  uralium,  or  somnal.  Phenyl  urethane,  H2N.CO.O(C6H5), 
is  a  light,  white  powder,  almost  insoluble  in  water,  very  soluble  in 
alcohol,  which  is  used  as  an  antipyretic  under  the  name  euphorine. 

The  primary  diamides  only  are  acyclic  compounds  (see  diamines, 
p.  298).  They  are  formed:  (1)  by  the  action  of  ammonia  upon  the 
neutral  esters.  Thus  ethyl  oxalate  yields  oxamide: 

CO.OC2H6  CO.NH, 

+     2NH,     =  +     2CH3.CH2OH. 

CO.OC2H6  CO.NH2 

(2)  By  heating  the  neutral  ammonium  salt  of  the  corresponding 
acid.  Thus  ammonium  carbonate  yields  carbamide: 

OC/ONH4  oc/NH'  2HO 

OC\ONH4  OC\NH2  2H'° 

Carbamide — Urea — H2N.CO.NH2 — exists  in  the  urine  of  mam- 
malia, and,  in  smaller  quantity,  in  the  excrement  of  birds,  fishes  and 
some  reptiles;  also  in  the  mammalian  blood,  chyle,  lymph,  liver, 
spleen,  lungs,  brain,  vitreous  and  aqueous  humors,  saliva,  perspira- 
tion, bile,  milk,  amniotic  and  allanto'ic  fluids,  and  in  serous  fluids. 

Urea  is  formed  by  the  methods  given  above;  also,  (1)  as  a 
product  of  decomposition  of  uric  acid,  usually  by  oxidation.  Thus 
nitric  acid  oxidizes  uric  acid  to  urea  and  alloxan: 

2C6H4N403+2H20+02=2CON2H4+2C4H2N204 

(2)  By  the  hydrolysis  of  creatine.     Thus  urea  and  sarcosine  are 
formed  by  the  action  of  KOH  upon  creatine : 

C4H9N302+H20=CON2H4+C3H7N02 

(3)  By  the  action  of  carbonyl  chloride  upon  dry  ammonia: 

COC12+2NH3=CON2H4+2HC1 

(4)  By  the  action  of  barium  hydroxide  upon  guanidine  (p.  301), 
or  upon  the  hexon  bases,  lysine  and  arginine,  products  of  decomposi- 
tion of  the  proteins. 

(5)  By  atomic  transposition  of  its  isomere,  ammonium  isocyanate, 
by  heat: 

0  :C  :N.NH^H2N.CO.NH2 

(6)  By  the   action   of   ammonia  upon   phosgene   or  upon   urea 
chlorides : 

COC12+4NH3=H2N.CO.NH2+2NH4C1,  or 
H2N.CO.C1+2NH3=H2N.CO.NH2+NH4C1 

(7)  By  heating  ammonium  carbamate  to  130°: 

H2N.CO.ONH4=H2N.CO.NH2+H20 


AMIDES  OP  DICARBOXYLIC  ACIDS  315 

(8)  "By  the  action  of  ammonia  upon  urethane: 

H2N.CO.O(C2H5)+NH3=H2N.CO.NH2+CH3.CH2OH 

Urea  crystallizes  in  long  rhombic  needles  or  prisms.  It  is  color- 
less and  odorless,  and  has  a  cooling  taste,  somewhat  resembling  that 
of  saltpeter.  It  is  neutral  in  reaction,  although  basic  in  character; 
soluble  in  one  part  of  water,  in  five  parts  of  cold  alcohol,  and  in  one 
part  of  boiling  alcohol,  sparingly  soluble  in  amylic  alcohol  and  in 
acetic  ether,  and  still  less  soluble  in  ether.  It  fuses  at  132°. 

When  heated  a  few  degrees  above  its  fusing  point  urea  appears 
to  boil,  giving  off  ammonia  and  ammonium  carbonate,  and  finally 
leaves  a  dry,  solid  residue,  consisting  of  ammelide,  C3H4N402, 
cyanuric  acid,  C303N3H3,  and  biuret,  C202N3H5.  This  residue,  dis- 
solved in  water,  gives  a  fine  red-violet  color  with  KOH  and  CuS04 
(Biuret  reaction).  When  added  to  a  concentrated  solution  of  fur- 
furole  and  hydrochloric  acid,  solid  urea  or  urea  nitrate  forms  a 
yellow  solution,  changing  in  color  to  green,  blue  and  intense  purple- 
violet.  After  a  time  the  mixture  thickens  and  blackens  (Schiff's 
reaction). 

Dilute  aqueous  solutions  of  urea  are  not  decomposed  by  boiling; 
but  if  the  solution  is  concentrated,  or  the  boiling  prolonged,  or  the 
temperature  raised  above  100°,  the  urea  is  partly  decomposed  into 
C02  and  NH3.  The  same  decomposition  takes  place  more  rapidly  and 
completely  under  pressure  at  140°.  It  is  also  caused  by  bacterial 
action  and  by  a  urinary  enzyme. 

Urea  is  decomposed  into  carbon  dioxide,  water  and  nitrogen  by 
the  alkaline  hypochlorites  and  hypobromites,  by  chlorine  and  by 
nitrous  acid.  Strong  acids  and  alkalies  decompose  it  into  carbon 
dioxide  and  ammonia. 

Urea  forms  definite  compounds,  not  only  with  acids,  but  also 
with  certain  salts  and  oxides.  Urea  nitrate — H2N.CO.NH3.N03— 
forms,  in  white  crystals,  when  a  concentrated  solution  of  urea  is 
treated  with  nitric  acid  in  the  cold.  It  is  much  less  soluble  than 
urea,  especially  in  presence  of  an  excess  of  nitric  acid.  It  is  decom- 
posed by  evaporation  of  its  solutions.  Urea  oxalate — CO:(NH3)2:- 
04C2 — separates  as  a  fine,  crystalline  powder,  from  mixed  concen- 
trated aqueous  solutions  of  urea  and  oxalic  acid.  Its  solutions  may 
be  evaporated  without  decomposition. 

When  solutions  containing  molecular  weights  of  urea  and  so- 
dium chloride  are  evaporated,  prismatic  crystals,  containing  CON2H4, 
NaCl+H20  are  obtained.  Urea  forms  several  compounds  with 
mercuric  oxide.  Of  these,  the  compound  (CON2H4)2,  4HgO,  con- 
taining 72  parts  of  HgO  for  10  parts  of  urea,  is  formed  as  a  white, 
amorphous  precipitate  when  a  dilute  solution  of  mercuric  nitrate  is 
gradually  added  to  a  dilute,  alkaline  solution  of  urea,  and  the  excess 
of  acid  neutralized  from  time  to  time. 


316  TEXT-BOOK   OF   CHEMISTRY 


THIOUREA  AND  THIOCARBAMIC  ACIDS. 

The  thio-compounds,  corresponding  to  carbamic  acid  and  to  urea, 
in  which  oxygen  is  replaced  by  sulphur,  exist  either  in  their  own 
forms  or  in  their  derivatives.  Thus  : 


0/SH  ~r  o.n 

°'0\NH2  S'C\NH2  S:C\NH2  S:\NH2 

Thiocarbamic   acid.        Sulphocarbamic   acid.    Dithiocarbamic    acid.  Thiourea. 

Thiocarbamic  acid  and  sulphocarbamic  acid  are  known  only  in 
their  esters.  Dithiocarbamic  acid  may  be  obtained  by  decomposition 
of  its  ammonium  salt,  which  is  produced  by  the  action  of  ammonia  in 

alcoholic  solution  upon  carbon  disulphide:  CS2+2NH3=S  :C  ^^HJ 

Similarly,   the   amine   salts   of   the   alkyl-dithiocarbamic    acids    are 

formed  by  the  action  of  the  primary  amines  upon  carbon  disulphide. 

Thiourea    is    obtained    by    heating    ammonium    isothiocyanate  : 

S:C:N(NH4)=S:C\^H22  ,  as  urea  is  obtained  from  the  isocyanate. 
It  is  also  formed  by  the  action  of  hydrogen  sulphide  upon  cyanamide  : 

H2S+CN.NH2=S  :C  <^H2. 

It  is  decomposed  by  boiling  acids  or  alkalies  into  C02,  NH3,  and 
H2S.  It  forms  salts,  and  alkyl,  phenyl  and  acidyl  derivatives  similar 
to  those  of  urea.  By  addition  with  alkyl  halides  thiourea  forms 
salts  of  alkyl  thiopseudoureas,  corresponding  to  pseudourea,  which 
are  used  in  certain  cyclic  syntheses: 

H2N.CS.NH2+C2H5C1=:HN  :C 

COMPOUND  UREAS. 

These  compounds,  which  are  exceedingly  numerous,  may  be  con- 
sidered as  derived  from  urea  by  the  substitution  of  one  or  more 
alcoholic  or  acid  radicals  for  hydrogen  atoms. 

Those  containing  alcoholic  radicals,   alkyl  ureas,  such  as  ethyl 

urea,  CK)\jJg!c,H,'  are  obtained:   (1)  By  the  action  of  primary  or 
secondary  amines  upon  isocyanic  esters: 

NH2.C2H5+0  :C  :N.C2H5=CO  :  (NH.C2H5)  2 

(2)  By  heating  the  isocyanic  esters  with  water,  the  amines  and 
carbonic  acid  being  formed  as  intermediate  products: 

OC  :N.C2H5+H20=NH2.C2H5+C02,  and 
OC  :N.C2H5+NH2.C2H5=CO  :  (NH.C2H5)  2 

(3)  By  condensation  of  amines  with  urea  chloride. 

Those  containing  acid  radicals  have  received  the  distinctive  name 
of  ureides.  Of  these,  some  are  monureides,  derived  from  a  single 


COMPOUND  UREAS  317 

molecule  t)f  urea,  others  diureides,  derived  from  two  molecules.  Some 
of  the  monurei'des  are  open  chain  compounds,  but  the  most  impor- 
tant of  them,  and  all  the  diurei'des  except  carbonyl  diurea  are  cyclic 
compounds,  derivatives  of  glyoxalin,  pyrimidin  or  cyanidin.  Thus 

CH2OH 

there  are  two  ureides,  corresponding  to  glyeollic  acid,    |  :  one, 

COOH 

hydantoic  acid,  an  open  chain  urei'de :  CO  \NHCH  COOH   »  the  other, 

/NH.CH2 
hydantoin,  a  cyclic  compound:  CO 

\NH.CO 

Only  the  acyclic  ureides  will  be  here  considered,  the  cyclic  ones 
will  be  referred  to  as  derivatives  of  their  parent  substances. 

The  monacidyl  monurei'des,  containing  a  single  acidyl,  are  formed  by  the 
action  of  acidyl  chlorides  or  anhydrides  upon  urea.  Thus  acetyl-urea  is  ob- 
tained with  acetyl  chloride: 

CH3.CO.C1+NH2.CO.NH2=H2N.CO.NH  ( CO.CH3 )  -f  HC1 
or  with  acetic  anhydride: 

( CO.CH3 )  2,0+2NH2.CO.NH2=2NH2.CO.NH  ( CO.CH3 )  -f  H2O. 

Mixed  ureides,  containing  an  alkyl  and  an  acidyl,  are  formed  in  like 
manner  from  alkyl-ureas.  Thus  methyl-urea  and  acetyl  chloride  form  methyl- 
acetyl-urea : 

CH3.NH.CO.NH2-f  CH3.CO.C1=:CH3.NH.CO.NH  ( CO.CH3 )  -f  HC1 

Such  mixed  ureides  are  also  formed  by  the  action  of  bromine  and  potassium 
hydroxide  upon  the  amides,  by  reactions  comparable  with  those  which  produce 
the  monamines  (p.  294).  Thus  methyl-acetyl-urea  is  formed  from  acetamide: 

2CH3.CO.NH2+Br2+2KOH=CH3.HN.CO.NH  (CO.CH3)  -(-2KBr-|-2H20 

The  diacidyl-urei'des  are  formed  by  the  action  of  phosgene  (carbonyl 
chloride)  upon  the  amides.  Thus  acetamide  yields  diacetyl-urea : 

2CH3.CO.NH2-f  COC12=  ( CH3.CO )  HN.CO.NH  ( CH3.CO )  -f  2HC1 

Allophanic  acid — H2N.CO.NH.COOH — the.  simplest  ef  the  acyclic  monu- 
rei'des, is  that  of  carbonic  acid,  HO.CO.OH,  and  is  known  only  in  its  esters. 

Biuret— H2N.CO.NH.CO.NH2— is  both  the  amide  of  allophanic 
acid,  and  the  monurei'de  of  carbamic  acid,  H2N.CO.OH.  It  is  formed 
by  heating  the  allophanic  esters  with  ammonia : 

H2N.CO.NH.COO(C2H5)+NH3=H2N.CO.NH.CO.NH2+ 
CH3.CH2OH 

By  condensation  of  urea  and  carbamic  acid: 

H2N.CO.NH2+HO.CO.NH2=H2N.CO.NH.CO.NH2+H20 

And  by  heating  urea  to  about  150  ° : 

2H2N.CO.NH2=H2N.CO.NH.CO.NH2+NH3 

When  further  heated  it  is  itself  decomposed  to  cyanuric  acid  and 
ammonia : 

3C2H5N302=2C3H3N303+3NH8 


318  TEXT-BOOK   OF   CHEMISTRY 

It  forms  crystals,  soluble  in  water,  f.  p.  190°.  It  is  chiefly  of 
interest  in  connection  with  the  biuret  reaction,  which  consists  in  the 
formation  of  a  red-violet  liquid  when  biuret  is  heated  with  a  dilute 
solution  of  CuS04  alkalinized  with  KOH  (see  Fehling's  test).  The 
reaction  is  due  to  the  formation  of  a  compound,  Cu[NH2(OH).CO.- 
NH.CO.NH2(OH)K]2,  which  has  been  obtained  in  red  crystals.  Or 
NiS04  may  be  used  in  place  of  CuS04,  in  which  case  an  orange  colored 
liquid  is  produced.  The  biuret  reaction  is  given  by  many  substances 
other  than  biuret,  such  as  malonamide,  oxamide,  aspartic  diamide, 
albumins,  albumoses,  peptones,  etc.,  and  is  considered  to  be  proof  of 
the  presence  in  the  substance  giving  it  of  two  amido-carbonyl  groups, 
CONH2,  attached  to  each  other,  or  to  N  or  C,  as  in : 


CONH2                      /CONH2  /CONH2 

HN  H2C 

CONH2                      \CONH,  \CONH3 

Oxamide.                         Biuret.  Malonamide. 


The  reaction  is  also  given  by  glycocol  amide  and  sarcosine  amide, 
which  contain  the  grouping:  H2N.CH2.CO.NH2. 

Hydantoi'c  Acid—Glycoluric  Acid — H2N.CO.NH.CH2.COOH— the  next  su- 
perior homologue  of  allophanic  acid,  is  the  acyclic  monurei'de  of  glycollic  acid, 
CH2OH.COOH,  and  is  obtained  as  its  Ba  salt  by  hydration  of  the  corresponding 
cyclic  monureide,  hydantoin,  by  BaH2O2.  (p.  395).  It  is  also  formed  by  con- 
densation of  urea  and  amido  acetic  acid  at  120°: 

H2N.CO.NH2-f-CH2NH2.COOH=H2N.CO.NH.CH2.COOH+NH3 

Oxaluric  Acid— H2N.CO.NH.CO.COOH— is  the  acyclic  monureide  of  oxalic 
acid,  and  is  obtained  in  its  salts  by  hydration  of  those  of  the  cyclic  monureide, 
oxalylurea.  The  free  acid  is  a  white,  crystalline  powder,  sparingly  soluble  in 
water.  It  is  easily  further  hydrolyzed  to  urea  and  oxalic  acid  by  heating  with 
alkalies,  or  even  with  water.  Its  ammonium  salts  exist  in  the  urine  in  small 
amount. 

Carbonyl    Diurea— H2N.CO.NH.CO.HN.CO.NH2— the   only   acyclic   diureide, 
is  formed  by  the  union  of  two  urea  molecules,  with  loss  of  H2,  by  the  carbonyl 
group,  brought  about  by  the  action  of  carbonyl  chloride  upon  urea: 
2H2N.CO.NH2-|-COC12=CO  ( HN.CO.NH2 )  2+2HCl. 

It  is  a  sparingly  soluble,  crystalline  powder,  which  is  split  by  heat  into 
cyanuric  acid  and  ammonia: 

C3H0NA=C3H3N803+NH3 

Imides  are  compounds  derivable  either  by  substitution  of  an  acidyleno  for 
H2  in  a  single  NH3  molecule,  or  by  substitution  of  the  imide  group,  NH,  for 
(OH)2  in  the  carboxyls  of  a  dicarboxylic  acid.  They  are  obtained  by  the  com- 
plete dehydration  of  the  ammonium  salts  of  the  acids,  or  similarly  from  the 
amic  acids  (see  pp.  312,  313).  Thus  monoammonic  succinate,  or  succinamic 
acid  yields  succinimide: 

CH2.COOH          CH2.CO\  CH2.COOH          CH2.CO\ 

NH+2H20,    or     I  NH-fH,0 

CH2.COO(NHJ   CH2.CO/  CH2.CONH2         CH2CO/ 

The  imides,  therefore,  except  carbimide,  corresponding  lo  carbonic  acid,  which  is 
isocyanic   acid,   O:C:N.H    (p.    307),   are    heterocyclic   compounds.      The    imides, 


NITROGEN  DERIVATIVES   OP  ALCOHOLS,   ETC.  319 

when  acted  upon  by  alkalies  or  baryta  water,  produce  the  salts  of  the  amic 
acids.  Thus  succinimide  and  caustic  potash  form  potassium  succinamate. 

NITROGEN  DERIVATIVES  OF  ALCOHOLS,  ALDEHYDES  AND  KETONES. 

Nitro  derivatives  of  the  alcohols,  aldehydes,  and  ketones  in  which 
the  N02  is  substituted  for  OH  or  for  0,  such  as  CH3.CH2(N02)  and 
CH3.CH(N02)2  and  CH3C(N02)2.CH3  are  mono-  or  dinitro-paraffins. 
Besides  these,  nitro  alcohols  are  also  known,  in  which  the  N02  is 
substituted  in  a  hydrocarbon  group,  e.g.,  nitro-ethyl  alcohol, 
CH2(N02).CH2OH. 

Amido-alcohols,  such  as  amido-ethyl  alcohol,  or  oxethylamine, 
CH2(NH2).CH2OH,  may  also  be  considered  as  derived  from  the 
glycols  by  substitution  of  NH2  for  OH.  These  are  the  oxyamines, 
hydroxamines,  hydramines,  or  oxyamine  bases,  among  which  are 
choline  and  neurine. 

Aldehyde-ammonia — Ethidene  Jiydroxamine  —  CH3.CH  \^H  — 
isomeric  with  ethylene  hydroxamine,  CH2(NH2).CH2OH,  may  be 
considered  as  an  amido-ethyl  alcohol  in  which  the  NH2  is  substituted 
for  H  in  the  methoxyl  group,  CH3.CH(NH2)OH.  It  is  obtained  by 
the  action  of  dry  NH3  upon  an  ethereal  solution  of  acetic  aldehyde: 
CH3.CHO+NH3=CH3.CH(NH2)OH.  It  is  a  crystalline  solid,  spar- 
ingly soluble  in  water,  alkaline,  f.  p.  80°. 

The  corresponding  compound  derivable  from  formic  aldehyde: 
H.CH(NH2)OH,  is  not  known;  but  when  formaldehyde  and  ammonia 
react  hexamethylene  tetramine,  (CH2)6N4,  is  produced:  6H.CHO+ 
4NH3=(CH2)6N4+6H20.  This  is  a  crystalline  solid,  very  soluble  in 
water,  which  decomposes  when  heated,  and  behaves  as  a  monacid 
base.  It  is  decomposed  by  weak  acids  and  by  acid  salts,  in  the 
reverse  manner  to  its  formation,  with  liberation  of  formic  aldehyde, 
a  reaction  which  is  probably  caused  by  the  acid  sodium  phosphate  of 
the  urine,  and  explains  its  action  as  a  urinary  antiseptic,  for  which 
purpose  it  is  used  under  the  names  formin  and  urotropin. 

Amido  aldehydes,  such  as  amido  acetaldehyde,  CH2(NH2).CHO, 
are  also  known. 

Acetonamines — The  action  of  ammonia  upon  acetone  causes  a 
condensation  of  two  or  three  molecules  of  acetone  with  one  of  ammo- 

C*TT   0*O  C*TT\ 

nia,  with  formation  of  diacetonamine :        3'(Cj^2//C.NH2,  a  colorless 

/  C*TT  C1  /  OTT  \  \ 

liquid;  and  triacetonamine :  OC^Q-^'Q  JQ-^j^/NH,  a  crystalline  solid, 
f.  p.  40°.  Triacetonamine  and  its  relative  vinyl  diacetonamine  are 
derivatives  of  piperidine,  and  are  the  nuclei  of  the  artificial 
local  anesthetics  OL  and  fi  eucaine.  Alkyl  derivatives  of  these 
are  formed  when  amines  are  used  in  place  of  ammonia.  Amido 
acetones,  or  amido  ketones,  such  as  CH3.CO.CH2(NH2),  amido 
acetone,  are  also  known. 


320  TEXT-BOOK   OF   CHEMISTRY 

Aldoximes,  and  ketoximes  or  acetoximes  are  isomeric  compounds 
derivable  from  the  aldehydes  and  ketones  by  substitution  of  the 
oxime  group,  =N.OH,  for  oxygen.  As  the  aldehydes  and  ketones  are 
derivatives  of  formic  aldehyde  by  substitution  of  alkyls  for  H,  so  the 
aldoximes  and  ketoximes  are  referable  to  carboxime,  the  oxime  of 
formic  aldehyde: 


OC   v.     -r  O\j  v     TT  \jyj  v     PITT 

\±1  \-tl  \Uri3 

Formaldehyde.  Acetaldehyde.  Dimethyl  ketone. 


\H 

Carboxime.  Aldoxime.  Ketoxime. 

They  are  formed  by  the  action  of  hydroxylamine  upon  aldehydes 
or  ketones  in  alkaline  solution,  the  aldoximes  more  readily  than  the 
ketoximes.  Thus  acetaldoxime  is  obtained  from  acetic  aldehyde: 

CH3.CHO+HONH2=CH3.CH  :NOH+H20 
and  acetoxime  from  dimethyl  ketone: 

CH3.CO.CH3+HONH2=CH3.C  (NOH)  .CH3+H20 

The  aldoximes  are  colorless  liquids,  miscible  with  water;  the 
ketoximes  crystalline  solids,  soluble  in  water. 

Nascent  hydrogen  reduces  both  aldoximes  and  ketoximes  to 
amines,  those  from  the  aldoximes  being  amines  of  primary  alcohols 
and  those  from  the  ketoximes,  amines  of  secondary  alcohols : 

CH3.CH  :NOH+2H2=CH3.CH2NH2+H20,  and 
CH3.C  (NOH)  .CH3+2H2=CH3.CHNH2.CH3+H20 

These  reactions  constitute  a  general  method  for  obtaining  amines 
(pp.  294,  296).  Both  aldoximes  and  ketoximes  are  hydrolyzed  to 
their  parent  substances  by  boiling  with  acids: 

CH3.CH  :NOH+H20=CH3.CHO+HONH2,  and 
CH3.C(NOH).CH3+H20=CH3.CO.CH3+HONH2 

The  principal  difference  between  aliphatic  aldoximes  and  ke- 
toximes is  in  their  behavior  towards  acidyl  halides  and  anhydrides, 
with  which  the  former  produce  nitriles,  and  the  latter  esters.  Thus 
with  acetaldoxime : 

CH3.CH  :NOH+CH3.COC1=CH3.CN+CH3.COOH+HC1,  or 
CH3.CH:NOH+(CH3CO)20=CH3.CN+2CH3.COOH; 

and  with  acetoxime: 

( CH3)  2C  :NOH+CH3.COC1=CH3.COO  [N  :C :  ( CH3)  2]  +HC1,  or 

(CH3)2C:NOH+(CH3.CO)20=:CH3.COO[N:C:(CH3)2] 

+CH3.COOH 

Acetyl  chloride  and  anhydride  cause  atomic  rearrangement  with 


NITROGEN   DERIVATIVES   OF   ACIDS  321 

acyclic  and  some  higher  aliphatic  ketoximes,  to  form,  phenyl  or  alkyl 
amidea:  cc.|>C:NOH=CHCfcHd>NH. 

Aldehyde  hydrazones  and  ketone  hydrazones  are  compounds  cor- 
responding to  the  aldoximes  and  ketoximes,  formed  by  condensation 
of  the  aldehydes  and  ketones  with  phenylhydrazine  (p.  379),  the 
bivalent  remainder  of  which,  =N.NH.C6H5,  is  substituted  for  oxygen. 
They  are  obtained  by  the  action  of  phenylhydrazine  upon  the  alde- 
hyde or  ketone  in  ethereal  solutions: 

CH3.CHO+H2N.NH.C6H5=CH3.CH :  (N.NH.C6H5)  +H20,   or 
(CH3)2  :CO+H2N.NH.C6H5=  (CH3)2  :C  :(N.NH.C6H5)  +H20 

NITROGEN  DERIVATIVES  OF  ACIDS. 

The  nitrogen  derivatives  of  the  pure  carboxylic  acids  are  numer- 
ous and  varied.  They  may  be  divided  into  two  classes:  (1)  Those  in 
which  nitrogen  or  a  nitrogen-containing  group  is  substituted  in  the 
carboxyl  for  OOH  or  for  OH,  and  (2)  those  in  which  the  substitution 
is  in  a  hydrocarbon  group.  The  first  class  includes  the  nitriles, 
amidines,  hydroxamic  acids,  amidoximes,  nitrolic  acids  and  amides, 
which  have  already  been  considered,  and  the  hydrazides,  which  are 
compounds  bearing  the  same  relation  to  the  hydrazines  (p.  302)  that 
the  amides  do  to  the  amines. 

The  following  are  included  in  the  second  class : 

Nitro-acids,  such  as  nitro-acetic  acid,  CH2(N02).COOH,  are  un- 
stable compounds,  usually  existing  only  in  their  esters  and  salts. 

Monamido-acids  are  much  more  stable,  and  include  a  number  of 
substances  of  physiological  interest.  They  are  derived  from  the  fatty 
acids  by  substitution  of  one  NH2  for  a  hydrogen  atom  in  a  hydrocar- 
bon group.  In  this  position  the  attachment  of  the  amido  group  is 
much  firmer  than  it  is  in  the  primary  monamides  in  which  it  replaces 
the  hydroxyl.  The  amides  are  easily  converted  into  ammonium  salts 
by  boiling  water: 

H2N.CO.CH3+H20=CH3.COO  (NHJ 

while  the  amido  acids  are  not  acted  upon. 

From  the  pure  carboxylic  acids,  amic  acids  (p.  313),  or  amides 
(p.  311)  amido-acids  are  derivable  by  substitution  of  HN2  for  OH 
or  for  H : 

CH3  CH3  CH2(NH2) 

COOH  CO(NH2)  COOH 

Acetic   acid.  Acetamide.  Amido-acetic    acid. 

COOH        CO(NH2)        CO(NH2)        COOH 
CH2          CH2  CH2  CH2(NH2) 

I          I  !  I 

COOH         COO(C2H5)       CO(NH2)         COOH 

Malonic   acid.  Malonamic  ester.  Malonamide.  Amido-malonic  acid. 


322  TEXT-BOOK   OF   CHEMISTRY 

From  the  monocarboxylic  oxyacids,  oxy amides  are  derived  by 
substitution  of  NH2  for  OH  in  COOH ;  amido-acids  of  the  same 
series  by  its  substitution  for  H  in  a  hydrocarbon  group ;  and  amido- 
acids  of  the  acetic  series  by  its  substitution  for  OH  in  a  CHOH  or  a 
CH2OH  group : 

CH,  CH2OH         CH8 

CHOH  CH2  CHOH 

COOH  COOH          CO(NH2) 

a  oxy  prop  ionic  0  oxypropionic  Lactamide 

(lactic)    acid.  (hydracrylic)    acid.  (oxyamide). 

CH2(NH2)          CH,  CH2(NH2) 

CHOH  *CH(NH3)       CH2 

COOH  COOH          COOH 

Amldo-lactlc  a  amido-propionic  ft  amido-propionic 

acid.  acid.  acid. 

The  first  amido-acid  of  the  fatty  series,  amido-formic  acid, 
NH2.CO.OH,  is  carbamic  acid.  The  third  and  superior  terms  of  the 
series  form  place  isomeres,  according  to  the  position  of  the  NH2 
group,  corresponding  to  the  oxyacids  and  similarly  designated  as 
a,  /?,  7,  etc.,  or  1-,  2-,  3-,  etc.  Those  acids  in  which  the  NH2  is  not 
attached  to  the  terminal  C  atom  contain  an  asymmetric  C*,  and 
therefore  exist  in  optical  isomeres.  The  fatty  amido-acids  are  also 
known  as  glycocolls  or  alanines.  They  are  obtained:  (1)  By  the 
action  of  ammonia  upon  the  monochloro  acids.  Thus  amido-acetic 
acid  is  obtained  from  monochloracetic  acid : 

CH2C1.COOH+NH3=CH2  (NH2)  .COOH+HC1. 

(2)  By   reduction   of  the   nitro   acids.     Thus   nitroacetic   ester, 
CH2(NO,).COO.C2H5,  yields  amido-acetic  ester. 

(3)  By  the  action  of  nascent  hydrogen  upon  the  cyan-fatty  acids: 

CN.COOH+2H2=CH2(NH2).COOH 

(4)  By  hydrolysis  by  HC1  of  the  nitriles  of  the  a  amido-acids: 
CH3.CHNH2.CN+2H20=CH3.CHNH2.COOH+NH3 

This  method  permits  of  the  formation  of  the  amido-acids  from  the 
corresponding  alcohols,  through  the  aldehydes. 

The  amido-acids  are  crystalline  solids,  most  of  which  are  sweet  in 
taste,  soluble  in  water,  insoluble  in  alcohol  or  in  ether,  neutral  in 
reaction.  As  they  contain  both  amido  and  carboxyl  groups,  they 
have  both  basic  and  acid  functions.  With  acids  they  form  ammonium 
salts.  They  form  stable  metallic  salts  with  bases,  but  their  esters 
are  unstable.  The  esters  retain  their  basic  function  and  form  more 
stable  hydrochlorides.  Stable  compounds  are,  however,  produced  by 


NITROGEN   DERIVATIVES   OF   ACIDS  323 

the  replacement  of  their  amido  hydrogen,  either  by  acidyls  or  by 
alkyls.  The  acidyl  compounds,  such  as  aeetyl  amido-acetic  acid, 
CH2.NH(C2H30).COOH,  are  formed  by  the  action  of  acidyl  chlorides 
upon  the  amido-acids ;  and  the  alkyl  derivatives,  such  as  methyl  gly- 
cocoll,  CH2.NH(CH3).COOH,  by  the  action  of  amines  upon  haloid 
fatty  acids.  On  dehydration  the  amido-acids  behave  like  the  oxy- 
acids,  which  are  also  both  basic  and  acid.  The  a  acids  on  dehydra- 
tion yield  cyclic  anhydrides,  which  are  ketopiperazines  and  which  on 
hydration  yield,  not  two  molecules  of  the  acid,  but  a  dipeptide.  The 
y  and  8  acids  yield  cyclic  esters,  called  lactams,  corresponding  to  the 
lactones.  The  resemblance  of  these  compounds  is  shown  by  the  fol- 
lowing formula?: 

CH2.NH2  CH2.NH.CO  CH2.OH  CH2COO 

COOH  CO.NH.CH2  COOH  COO— CH2 

Amido-acetic  Glycocoll  Glycollic  Glycollide 

acid.  anhydride.  acid.  (lactide.) 

CH2NH2  CH2NH  CH2.OH  CH2 


CH2  CH2 

CH2  in2 

COOH  CO 


CH2  CH2 

CH3  CH2 

COOH  COO  , 


Y  amido-butyric  y  butyro-  Y  oxy-butyric  -y  butyro- 

acid.  lactam.  acid.  lactone. 

The  formation  of  the  lactams  is  another  instance  of  the  pro- 
duction of  closed  chain  from  open  chain  compounds. 

By  dry  distillation  the  amido  acids  are  split  to  amines  and  carbon 
dioxide : 

CH2NH2.COOH=CH3.NH2+C02 

When  heated  with  hydriodic  acid  at  200°  they  are  reduced  to 
fatty  acids : 

CH2NH2.COOH+H2=CH3.COOH+NH3 

Amido  acids  of  the  acetic  and  oxalic  series  are  converted  into  the 
corresponding  monochlor  acid  by  nitrosyl  chloride: 

CH2NH2.COOH+NOC1=CH2C1.COOH+N2+H20 

Nitrous  acid  acts  upon  the  <*-amido  acids  according  to  the  re- 
action characteristic  of  the  amido  group  converting  them  into  oxy- 
acids,  with  evolution  of  free  nitrogen : 

CH2NH2.COOH+HN02=CH2OH.COOH+N2+H20 

This  conversion  of  amido  into  oxyacids,  which  probably  occurs 
in  the  animal  organism,  is  referred  to  as  deamidation. 

Amido-acetic  Acid — Glycocoll — Glycine — Glycolamic  acid — Gela- 
tin sugar — CH2.NH2.COOH — was  first  obtained  by  the  action  of 


324  TEXT-BOOK   OF    CHEMISTRY 

H2S04  upon  gelatin.  It  is  formed  by  the  action  of  KOH  upon  glue  ; 
and,  synthetically,  by  the  methods  given  above  and  by  the  union  of 
formic  aldehyde,  hydrocyanic  acid  and  water: 

H.CHO+HCN+H20=CH2(NH2).COOH 

It  is  produced  along  with  benzoic  acid,  in  the  decomposition  of 
hippuric  acid  (p.  375)  ;  as  a  product  of  decomposition  of  glycocholic 
acid;  and  by  the  action  of  hydriodic  acid  upon  uric  acid  (p.  406). 
It  occurs  uncombined  in  the  muscle  of  the  scallop. 

It  appears  as  large,  colorless,  transparent  crystals;  has  a  sweet 
taste;  fuses  at  170°;  sparingly  soluble  in  cold  water;  much  more 
soluble  in  warm  water;  insoluble  in  absolute  alcohol  and  in  ether. 

It  forms  crystalline  salts  with  acids,  which  are  decomposed  at  a 
boiling  temperature.  Nitric  acid  oxidizes  it  to  glycollic  acid.  It  is 
very  resistant  to  oxidation  by  KMn04  in  acid  solution,  but  in  alkaline 
solution  or  in  its  esters  it  is  readily  oxidized  to  urea: 

2CH2NH2.COOH+302=H2N.CO.NH2+3C02+3H20 

from  which  it  is  presumed  that  the  free  acid  does  not  exist  as 
such,  but  as  a  lactam.  Its  acid  function  is  more  marked;  it  expels 
carbonic  and  acetic  acids  from  calcium  carbonate  and  lead  acetate. 
It  dissolves  cupric  hydroxide  in  alkaline  solution,  and  there  is  no  re- 
duction on  boiling  the  solution;  but  on  addition  of  alcohol  to  the 
cold  solution,  blue  crystalline  needles  of  copper  glycolamate  separate. 
With  ferric  chloride  it  gives  an  intense  red  color,  which  is  discharged 
by  acids,  and  restored  by  ammonia.  With  phenol  and  sodium  hypo- 
chlorite  it  gives  a  blue  color,  as  does  ammonia.  It  forms  esters  and 
amides.  Its  methylic  ester  is  isomeric  with  sarcosine.  Heated  under 
pressure  with  benzoic  acid  it  forms  hippuric  acid.  Fused  with  urea 
it  forms  glycolylurea  and,  ultimately,  uric  acid. 

Methyl-glycocoll—  Sarcosine—  CH2.NH(CH3).COOH  --  isomeric 
with  alanine,  the  methyl  ester  of  glycocoll,  and  lactamide,  is  not 
known  to  exist  as  such  in  animal  nature,  but  it  may  be  obtained  from 
creatine  by  the  action  of  barium  hydroxide: 


+     H20     =     CH2.NH(CH,).COOH4-H2N.CO.NH2 

It  is  formed  by  the  action  of  methylamine  upon  monochloracetic  acid  : 
CH2C1.COOH+CH3.H2N=CH2.NH(CH3).COOH+HC1. 

It  crystallizes  in  colorless,  transparent  prisms;  very  soluble  in 
water  ;  sparingly  soluble  in  alcohol  .and  ether.  Its  aqueous  solution 
is  not  acid,  and  has  a  sweetish  taste.  It  forms  salts  with  acids,  but  it 
is  not  known  to  form  metallic  salts.  It  unites  with  cyanamide  to 
form  creatine;  and  with  cyanogen  chloride  to  form  methylhy- 
dantoine. 


NITROGEN   DERIVATIVES   OF   ACIDS  325 

Amido-propionic  Acids— Alanines — Two  are  known:  a  alanine,  CH3. 
CH(NH2).COOH,  formed  by  the  reduction  of  a  nitroso-propionic  acid;  and  /3 
alanine,  CH2(NH2)  .CH2.COOH,  formed  either  by  the  reduction  of  /3  nitroso- 
propionic  acid,  or  by  the  action  of  ammonia  upon  /3  iodo-propionic  acid. 
Neither  is  known  to  exist  in  nature.  Nitrous  acid  converts  the  two  alanines 
into  the  corresponding  lactic  acids. 

Amido-butyric  Acids  —  C4H9N02 — and  Amido-valeric  acids  —  CglT^NG^  — 
are  mainly  of  theoretic  interest.  Alpha  amido-n-valeric  acid,  CH3.CH2.CH2.- 
CH(NH2).COOH,  is  a  product  of  oxidation  of  coni'ine.  Alpha  amido-iso-valeric 

acid Butalanine,     ( CH3 )  2 :  CH.CHNH2.COOH    occurs    in    the    pancreas,    and    is 

formed  as  a  product  of  decomposition  of  fibrin  and  of  certain  proteins. 

Amido-caproic  Acids — Leucines. — Twenty-seven  isomeric  amido 
acids  are  derivable  from  the  seven  caproic  acids;  and  this  number 
is  still  further  increased  by  the  fact  that  in  many  of  these  the  intro- 
duction of  the  amido  group  renders  a  carbon  atom  asymmetric  (see 
formula  of  a  amido-propionic  acid,  p.  322).  The  leucine,  which  is  of 
physiological  interest  as  a  product  of  decomposition  of  the  proteins, 
is  the  laevo  a  amido-isobutyl-acetic  acid,  (CH3)2:CH.CH2.*CH 
(NH2).COOH,  as  is  demonstrated  by  its  synthetic  formation  from 
isovaleric  aldehyde,  (CH3)2:CH.CH2.CHO: 

2(CH3)2.CH.CH2.CH2OH+02=2(CH3)2.CH.CH2.CHO+2H20 
(CH3)  2  :CH.CH2.CHO+CN.NH4=  (CH3)  2  :CH.CEUCHNH2.- 

CN+H20 

(CH3)2:CH.CH2.CHNH2.CN+2H9O^(CH3)2:CH.CH2.- 
CHNH2.COOH+NH2 

The  corresponding  dextro-acid  has  been  obtained  by  the  action  of 
Penicillium  glaucum  upon  the  inactive  acid;  and  the  Ia3vo-acid, 
known  as  "vegetable  leucine"  from  the  vegetable  globulin,  conglutin. 

f^TT  \ 

d-isoleucine  —  methyl-ethyl-tf -amido  propionic  acid — c2nl/~ 
CH.CHNH2.COOH— is  also  a  product  of  hydrolysis  of  proteins,  and 
is  formed  synthetically  by  the  same  methods  as  leucine,  starting  with 

secondary  butyl  carbinol    <?H£>  CH.CH2OH. 

"Animal  leucine"  is  produced,  accompanied  by  tyrosine,  in  the 
decomposition  of  proteins  by  boiling  with  dilute  acids  or  alkalies,  by 
fusion  with  caustic  alkalies,  by  putrefaction,  and  by  trypsin  diges- 
tion. It  appears  to  exist  also  as  a  normal  constituent  of  the  pancreas, 
spleen,  thymus,  lymphatic  and  salivary  glands,  liver  and  kidneys. 
Pathologically  the  quantity  of  leucine  is  much  increased  in  the  liver 
in  diseases  of  that  organ,  in  typhus  and  in  variola;  in  the  bile  in 
typhus ;  in  the  blood  in  leukemia,  and  in  yellow  atrophy  of  the  liver ; 
in  the  urine  in  yellow  atrophy  of  the  liver,  in  typhus,  in  variola,  and 
in  phosphorus  poisoning;  in  choleraic  discharges  from  the  intestine; 
in  pus ;  in  the  fluids  of  dropsy  and  of  atheromatous  cysts. 

Leucine  crystallizes  from  alcohol  in  soft,  pearly  plates,  lighter 
than  water,  and  somewhat  resembling  cholesterol;  sometimes  in 


326  TEXT-BOOK   OF   CHEMISTRY 

rounded  masses  of  closely  grouped,  radiating  needles.  Pure  leucine 
is  sparingly  soluble  in  water,  almost  insoluble  in  alcohol  and  ether, 
but  readily  soluble  in  hot  water  or  alcohol.  When  impure  it  is  more 
soluble.  It  io  odorless  and  tasteless,  and  its  solutions  are  neutral. 
It  dissolves  readily  in  acids  and  alkalies,  forming  crystalline  com- 
pounds with  the  former.  It  fuses  and  sublimes  at  170°  without  de- 
composition, but  at  a  slightly  higher  temperature  is  decomposed  into 
amylamine  and  carbon  dioxide. 

When  heated  with  hydriodic  acid  under  pressure  the  leucines  are 
decomposed  into  ammonia  and  the  corresponding  caproic  acids.  By 
nitrous  acid  they  are  oxidized  to  the  corresponding  oxycaproic,  or 
leucic  acids,  C6H1203,  with  elimination  of  water  and  of  nitrogen. 
Hot  solutions  of  leucine  form  precipitates  with  hot  solutions 
of  cupric  acetate.  They  dissolve  cupric  hydroxide,  but  do  not 
reduce  it  on  boiling.  When  boiled  with  solution  of  neutral  lead  ace- 
tate and  carefully  neutralized  with  ammonia,  they  deposit  brilliant 
crystals  of  a  compound  of  leucine  and  lead  oxide.  When  HN03  is 
slowly  evaporated  in  contact  with  leucine  on  platinum  foil  a  colorless 
residue  remains,  which,  when  warmed  with  NaOH  solution,  turns 
yellow  or  brown,  and  on  further  concentration,  forms  oily  drops, 
which  do  not  adhere  to  the  platinum  (Scherer's  reaction).  Solution 
of  leucine,  when  heated  with  solution  of  mercurous  nitrate,  liberates 
metallic  mercury  (Hofmeister's  reaction). 

PHOSPHORUS,  ANTIMONY,  AND  ARSENIC  DERIVATIVES. 

Many  organic  compounds,  similar  to  those  containing  nitrogen,  in 
which  that  element  is  replaced  by  phosphorus,  antimony,  or  arsenic, 
are  known.  Of  these  only  a  few  arsenic  derivatives  require  mention. 

Dimethyl  Arsine — (CH3)2HAs  —  corresponding  to  dimethyl 
amine,  (CH3)2HN,  is  a  colorless  liquid,  having  an  intensely  dis- 
agreeable odor,  which  ignites  spontaneously  in  air.  It  may  be  con- 
sidered as  the  hydride  of  a  radical,  (CH3)2As,  which,  from  the  dis- 
agreeable odor  and  intensely  poisonous  action  of  all  of  its  com- 
pounds, has  received  the  name  cacodyl.  As  the  amines  are  considered 
as  derived  from  ammonia  by  substitution  of  alkyl  groups  for  the 
hydrogen,  so  the  compounds  of  which  this  is  a  type  are  derived  from 
the  corresponding  hydrogen  compounds  of  phosphorus,  antimony, 
and  arsenic,  and  are  called  phosphines,  stibines,  and  arsines. 

The  parent  substance  of  the  arseno-organic  compounds  is  a 
fuming,  foul-smelling  liquid,  obtained  by  distilling  a  mixture  of 
arsenic  trioxide  and  potassium  acetate,  and  called  fuming  liquid  of 
Cadet.  The  principal  constituent  of  this  is  cacodyl  oxide,  or  alkar- 
sine,  (CHj'la/0'  a  liquid  which  boils  at  120°,  insoluble  in  water, 
soluble  in  alcohol  and  in  ether.  Cacodyl,  or  dicacodyl,  (CH3)2As.- 
As(CH3)2  is  a  colorless,  insoluble  liquid,  which  boils  at  170°  and 


UNSATURATED   ALIPHATIC    COMPOUNDS  327 

ignites  spontaneously  in  air.  Cacodyl  and  most  of  its  compounds 
are  exceedingly  poisonous,  especially  the  cyanide  (CH3)2.As(CN), 
an  ethereal,  volatile  liquid  the  presence  of  whose  vapor  in  air,  even  in 
minute  traces,  produces  symptoms  referable  both  to  arsenic  and  to 
cyanogen.  Probably  minute  quantities  of  arsines  are  formed  during 
the  putrefaction  of  cadavers  embalmed  with  arsenical  liquids. 

Cacodylic  acid  (CH3)2:As.O.OH.  is  formed  by  oxidation  of 
cacodyl  oxide  by  HgO  in  presence  of  water: 

( CHJ  ;ls>  0+2HgO+H20=2  ( CH3 )  2As.OOH+Hg2 

It  is  easily  soluble  in  water;  it  is  acid,  odorless,  and  crystallizes 
in  prisms.  It  is  not  attacked  by  nitric  acid  or  even  by  aqua  regia. 
Its  salts  are  soluble  in  water  and  crystallize  with  difficulty.  Its  Na 
salt  is  used  in  medicine. 


UNSATURATED  ALIPHATIC  COMPOUNDS. 

In  this  class  are  included  all  open  chain  carbon  compounds  in 
which  two  carbon  atoms  exchange  more  than  one  valence  (p.  197). 
As  the  saturated  compounds  consist  of  the  members  of  the  first,  or 
methane,  series  of  hydrocarbons  and  their  derivatives,  so  the  un- 
saturated  compounds  are  the  remaining  series  of  open  chain  hydro- 
carbons and  their  unsaturated  derivatives  (p.  201). 

HYDROCARBONS,  ETHENE,  OR  OLEFINE  SERIES. 

The  members  of  this  series  contain  two  atoms  of  carbon  less  than 
the  corresponding  terms  of  the  methane  series.  They  may  be  modi- 
fied by  addition,  behaving  as  bivalent  radicals,  as  well  as  by  substitu- 
tion. Their  "Geneva"  names  terminate  in  ene. 

Ethene— Ethylene— Olefiant  gas—Olefine—Elayl—C'H.2:C~K2—is 
formed  by  the  dry  distillation  of  fats,  resins,  wood,  and  coal,  and  is 
a  valuable  constituent  of  illuminating  gas. 

It  is  formed  synthetically:  (1)  By  heating  a  mixture  of  alcohol, 
H2S04  and  sand.  In  this  reaction  ethyl-sulphuric  acid  is  formed  and 
decomposed : 

C2H5.HSO^=H2S04+CH2  :CH2 

(2)  By  the  action  of  caustic  potash  upon  ethyl  bromide: 

CH3.CH2Br+KOH=KBr+H20+CH2  :CH2 

(3)  By  heating  together  acetylene  and  hydrogen,  or  by  the  action 
of  nascent  hydrogen  upon  copper  acetylide: 

CHiCH+H2=CH2:CH2,  or  C2Cu2+2H2=CH2:CH2+2Cu 

(4)  By  heating  methylene  iodide  with  copper: 

2CH2I2+2Cu:=CH2  :CH2+2CuI2 


328  TEXT-BOOK   OF   CHEMISTRY 

(5)  By  the  action  of  sodium,  of  zinc  or  of  magnesium  upon 
ethylene  bichloride  or  bibromide: 

CH2Cl.CH2Cl+Na2=CH2  :CH2+2NaCl,  or 

CH2Br.CH2Br+Zn=CH2:CH2-fZnBr2,  or 

CH2Br  :CH2Br+Mg=MgBr2+CH2  :CH2 

It  is  a  colorless  gas,  tasteless,  has  a  faint  odor  of  salt  water,  spar- 
ingly soluble  in  water.  Its  critical  temperature  is  13°;  its  critical 
pressure  60  atmospheres.  It  boils  at  — 105°. 

It  burns  with  luminous  flame,  and  forms  explosive  mixtures  with 
air.  By  long  contact  with  a  red-hot  surface  it  is  decomposed  into 
acetylene,  methane,  ethane,  a  tarry  product,  and  carbon.  It  unites 
with  hydrogen  to  form  ethane,  C2H6;  with  oxygen  it  unites  explo- 
sively on  approach  of  flame,  to  form  carbon  dioxide  and  water.  It 
combines  with  hydrobromic  and  hydriodic  acids  to  form  ethyl 
bromide,  C2H5Br,  and  ethyl  iodide,  C2H5I.  It  combines  with  sul- 
phuric acid  to  form  ethyl-sulphuric  acid:  CH2 :CH2-}-H2S04= 
C2H5.HS04.  Mixtures  of  ethene  and  chlorine  explode,  with  copious 
deposition  of  carbon,  on  approach  of  flame.  In  diffuse  daylight  they 
unite  slowly,  with  separation  of  an  oily  liquid,  ethylene  chloride,  or 
Dutch  liquid,  CH2C1.CH2C1,  to  whose  formation  the  name  "olefiant 
gas"  is  due.  The  same  compound  is  formed  when  ethene  is  passed 
through  a  mixture  of  Mn02,  NaCl,  H2S04,  and  H20.  When  passed 
through  alkaline  solution  of  potassium  permanganate,  it  is  oxidized 
to  oxalic  acid  and  water: 

2CH2  :CH2+502=2COOH.COOH+2H20 

Or,  by  careful  oxidation  by  dilute  solution  of  the  same  agent,  it 
forms  ethene  glycol: 

2CH2:CH2+2H20+02=2CH2OH.CH2OH  (p.  222). 

When  inhaled,  diluted  with  air,  ethene  produces  effects  some- 
what similar  to  those  of  nitrous  oxide. 

Two  groupings  of  (C2H4)"  are  possible, — CH2.CH2 — ,  and 
CH3.CH=,  the  former  produced  by  the  breaking  of  the  double  bond 
between  the  carbon  atoms  in  ethene,  the  latter  by  double  substitution 
in  ethane.  Compounds  containing  the  grouping — CH2.CH2 — are 
designated  as  ethylene  or  ethene  compounds,  e.g.,  ethylene  chloride, 
C1CH2.CH2C1,  b.  p.  84°,  those  containing  the  grouping  CH3.CH=  are 
called  ethidene  or  ethylidene  compounds,  e.g.,  ethidene  chloride, 
CH3.CHC12,  b.  p.  58°. 

Homologues  of  Ethene. — The  superior  homologues  of  ethene 
exist  in  coal  gas  and  coal  tar.  They  are  formed  by  the  methods  1 
and  2,  used  for  the  preparation  of  ethene,  but  starting  from  the  cor- 
responding superior  monoatomic  alcohol.  The  lower  terms  are  gas- 
eous, the  higher  liquid  at  the  ordinary  temperature.  They  undergo 
reactions  similar  to  those  of  ethene,  and  in  addition,  readily  poly- 


UNSATURATED   ALIPHATIC    COMPOUNDS  329 

merize  under  the  influence  of  sulphuric  acid,  zinc  chloride  and  other 
substances. 

ETHINE,  OR  ACETYLENE  SERIES. 

Acetylene — Ethine — HCiCH — exists  in  coal  gas,  and  is  formed 
in  the  decomposition  by  heat  or  otherwise,  of  many  organic  sub- 
stances. It  is  formed:  (1)  By  passing  an  electric  arc  in  an  atmos- 
phere of  hydrogen : 

2C+H2=CHiCH 

This  is  the  only  known  synthesis  of  a  hydrocarbon  directly  from 
the  elements. 

(2)  By  the  action  of  water  upon  calcium  carbide: 

C2Ca+2H20=HCiCH+CaH202 

This  method  is  used  industrially  for  the  preparation  of  acetylene 
for  use  as  an  illuminating  gas. 

(3)  By  heating  chloroform,  bromoform  or  iodoform  with  sodium, 
copper,  silver  or  zinc: 

2CHCl3+3Na2=6NaCl-fHCiCH 

(4)  By  heating  ethylene  bromide  with  caustic  potash.     The  re- 
action occurs  in  two  phases,  vinyl  bromide  being  formed  as  an  inter- 
mediate product : 

CH2Br.CH2Br+KOH=CHBr  :CH2+KBr+H20,  and 
CHBr  :CH2+KOH=CH:CH+KBr+H20 

Acetylene  is  a  colorless  gas,  rather  soluble  in  water,  having  a 
peculiar,  disagreeable  odor,  that  which  is  observed  when  a  Bunsen 
burner  burns  within  the  tube.  This  gas  contains  as  impurities  com- 
pounds of  S,  P,  and  Si,  which  must  be  removed  if  it  is  to  be  used 
indoors.  It  is  liquefied  by  a  pressure  of  48  atmospheres  at  0°.  It 
forms  explosive  mixtures  with  air  or  oxygen.  In  contact  with  a  red- 
hot  surface,  and  in  absence  of  air,  it  polymerizes  to  benzene  3C2H2= 
C6H6,  an  action  which  accounts  for  the  presence  of  benzene  in  gas 
tar,  and  which  is  of  great  interest  in  connection  with  the  relations 
between  the  open  chain  and  the  closed  compounds.  Nascent  hydrogen 
converts  acetylene  into  ethene,  C2H4,  and  then  into  ethane,  C2H6. 
Under  the  influence  of  the  electric  discharge,  it  combines  with  nitro- 
gen to  form  hydrocyanic  acid :  C2H2+N2=2CNH.  It  combines  with 
HC1  and  with  HI  to  form  ethidene  chloride,  CH3.CHC12,  or  iodide, 
CH3.CHI2.  Mixed  with  chlorine  it  detonates  violently  in  diffuse  day- 
light. The  hydrogen  atoms  of  acetylene  may  be  replaced  by  metals 
to  form  acetylides,  or  carbides.  Sodium  and  calcium  acetylides  are 
stable  at  high  temperatures,  but  are  decomposed  by  water  with  for- 
mation of  acetylene.  Silver  and  copper  acetylides  are  highly  ex- 
plosive when  dry,  and  explosions  which  have  occurred  when  illumi- 


330  TEXT-BOOK   OF   CHEMISTRY 

nating  gas  was  in  contact  with  brass  or  copper  were  probably  due 
to  the  formation  of  the  latter.  The  formation  of  copper  acetylide, 
which  separates  as  a  blood-red  precipitate  when  acetylene  is  con- 
ducted through  a  solution  of  cuprous  chloride,  is  utilized  as  a  test  for 
the  presence  of  acetylene.  Acetylene  mercuric  chloride,  C2(HgCl)2, 
separates  as  a  non-explosive,  white  precipitate  when  acetylene  is 
passed  through  a  solution  of  mercuric  chloride. 

DIOLEFINE  AND  SUPERIOR  SERIES. 

The  diolefines  are  isomeric  with  the  hydrocarbons  of  the  acetylene  series, 
containing  two  double  linkages,  in  place  of  one  triple  linkage.  Thus  allene,  or 
allylene,  CH2:C:CH2,  is  isomeric  with  propine,  or  propylene,  CH|C.CH3. 

Trimethyl-ethylene — Pentene — Amylene — Valerene  —  ( CH3 )  2 :  C :  CH.CH3 — is 
a  colorless,  mobile  liquid,  boiling  at  39°,  obtained  by  heating  alcohol  with  a  con- 
centrated solution  of  zinc  chloride.  It  is  used  as  an  anesthetic,  and  in  the 
preparation  of  tertiary  amylic  alcohol. 

UNSATURATED  OXIDATION  PRODUCTS  OF  UNSATURATED 
HYDROCARBONS. 

Like  the  paraffins,  the  defines,  acetylenes,  diolefines,  etc.,  yield  alcohols, 
aldehydes,  ketones,  acids,  oxides,  and  esters. 

Allyl  Alcohol— CH2:CH.CH2OH— is  formed:  ( 1 )  By  the  action  of  sodium 
upon  dichlorhydrine : 

CH2C1.CHC1.CH2OH+ Na2=CH2 :  CH.CH2OH+2NaCl 

(2)  By  heating  allyl  iodide  with  water: 

CH2 :  CH.CHJ+ H20=CH2 :  CH.CH2OH+HI 

(3)  By  reduction  of  acroleln  by  nascent  hydrogen: 

CH2 :  CH.CHO+H2=CH2 :  CH.CH2OH 

(4)  By  heating  glycerol  with   formic  acid,   which   first   forms   a   glycerol 
ester,  which  then  splits  to  allylic  alcohol,  carbon  dioxide  and  water: 

CH2OH.CHOH.CH2  ( OOC.H )  =CH2OH.CH  :CH2-f  CO2+H20 

Oxalic  acid,  which  yields  formic  acid,  may  be  used  in  place  of  the  latter. 

It  is  a  colorless,  mobile  liquid,  solidifies  at  — 50°,  boils  at  97°,  sp.  gr.  0.8507 
at  25°,  soluble  in  water,  has  an  odor  resembling  the  combined  odors  of  alcohol 
and  essence  of  mustard,  burns  with  a  luminous  flame.  It  is  isomeric  with 
propylic  aldehyde  and  with  acetone.  Oxidizing  agents,  such  as  silver  oxide, 
convert  it  first  into  the  corresponding  aldehyde,  acroleme,  then  into  the  acid, 
acrylic  acid.  It  does  not  unite  readily  with  hydrogen,  but,  in  presence  of 
nascent  H,  union  takes  place  slowly,  with  formation  of  normal  propyl  alcohol. 
It  forms  products  of  addition  with  chlorine,  bromine,  and  iodine,  similar  to 
those  derived  from  glycerol. 

Acrylic  Aldehyde— Acroleine— CH2 :  CH.CHO— the  first  of  the  series  of 
olcfine  aldehydes,  is  the  substance  which  causes  the  disagreeable  odor  developed 
when  fats  or  oils  are  overheated.  It  is  formed:  (1)  By  oxidation  of  allylic 
alcohol;  (2)  by  distilling  glycerol  with  strong  H2S04  or  with  KHS04: 

CII2OH.CHOH.CH2OH=CH2 :  CH.CHO+2H2O 

Acroleine  is  a  colorless  liquid,  having  a  pungent  odor,  and  giving  off  a 
vapor  which  is  intensely  irritating;  sp.  gr.  0.841  at  20°,  boils  at  52°,  soluble 


UNSATURATED  ALIPHATIC    COMPOUNDS  331 

in  2-3  parts  of  water.  Oxidizing  agents  convert  it  into  acrylic  acid.  Nascent 
hydrogen  reduces  it  to  allyl  alcohol.  It  does  not  combine  with  alkaline  bisul- 
phites. It  reduces  ammoniacal  silver  nitrate  solution  as  does  acetic  aldehyde. 
It  suffers  change  even  when  kept  in  closed  vessels,  and  deposits  a  white,  flocculent 
material,  which  is  called  disacryl,  while  formic,  acetic  and  acrylic  acids  are 
also  produced. 

Oleic  Acids. — The  acids  of  this  series  are  monocarboxylic  acids 
derived  from  the  defines,  and  contain  two  atoms  of  hydrogen  less 
than  the  corresponding  terms  of  the  acetic  series.  They  are  formed : 
(1)  By  oxidation  of  their  corresponding  alcohols  or  aldehydes.  Thus 
allylic  alcohol,  CH2:CH.CH2OH,  or  acroleine,  CH2:CH.CHO,  yields 
acrylic  acid,  CH2:CH.COOH. 

(2)  By  the  action  of  alcoholic  KOH  upon  the  monohalogen  fatty 
acids.    Thus  ft  monobromo  propionic  acid  yields  acrylic  acid: 

CH2Br.CH2.COOH+KOH=CH2:CH.COOH+KBr+H20 

(3)  By  dehydration  of  acids  of  the  oxy acetic  series.     Thus  ethy- 
lene  lactic  acid  forms  acrylic  acid  when  heated: 

CH2OH.CH2.COOH=CH2  :CH.COOH+H20 

(4)  From  the   allyl  halides,   by  conversion   into   cyanides   and 
saponification.    Thus  crotonic  acid  is  obtained  from  allyl  iodide: 

CH2  :CH.CH2I+KCN=CH2  :CH.CH2CN+KI,  and 
CH2  :CH.CH2CN+2H20+HC1=CH2  :CH.CH2.COOH+NH4C1 

The  oleic  acids  combine  with  the  hydracids  to  form  monohalogen 
fatty  acids,  the  halogen  assuming  the  position  furthest  removed  from 
the  carboxyl.  Thus  acrylic  acid  and  hydriodic  acid  form  ft  iodo 
propionic  acid: 

CH2  :CH.COOH+HI=CH2I.CH2.COOH 

Heated  with  caustic  alkalies  to  100°,  they  form  oxyacids.  Thus 
acrylic  acid  forms  «  lactic  acid: 

CH2  :CH.COOH+KOH=CH3.CHOH.COOK 

But,  when  fused  with  caustic  alkalies,  they  are  decomposed  into 
fatty  acids,  with  loss  of  H.  Thus  acrylic  acid  yields  formic  and 
acetic  acids : 

CH2:CH.COOH+2KOH=H.COOK+CH3.COOK+H2 

The  fty  acids,  i.e.,  those  in  which  the  double  bond  is  between  the 
ft  and  y  positions,  as  in  ethidene  propionic  acid,  CH3.CH:CH.CH2. 
COOH,  when  heated  with  H2S04  form  lactones. 

Acrylic  Acid — CH2:CH.COOH — is  best  obtained  by  oxidizing 
acroleine  with  silver  oxide.  It  is  a  liquid  below  7°,  boils  at  140°, 
mixes  with  water,  and  has  an  odor  like  that  of  acetic  acid. 

Oleic  Acid—  CH8.(CH2)7.CH:CH.(CH2)7.COOH— exists  as  its 
glyceric  ester  in  fats  and  fixed  oils,  and  is  obtained  in  an  impure 


332  TEXT-BOOK   OF   CHEMISTRY 

form,  on  a  large  scale,  as  a  by-product  in  the  manufacture  of  stearin 
candles. 

Pure  oleic  acid  is  a  white,  pearly,  crystalline  solid,  fuses  at  14°, 
odorless,  tasteless,  soluble  in  alcohol  and  in  ether,  insoluble  in  water, 
sp.  gr.  0.808  at  19°,  and  neutral  in  reaction.  Exposed  to  air,  the 
liquid  acid  absorbs  oxygen,  and  becomes  yellow,  rancid  in  taste  and 
odor,  acid  in  reaction,  and  incapable  of  solidification  on  cooling. 
Nitric  acid  oxidizes  it,  with  formation  of  the  lower  fatty  acids  and 
sebacic  acid,  C10H1804.  Heated  to  200°  with  excess  of  caustic  potash, 
it  is  split  into  palmitic  and  acetic  acids: 

C18H3A+2KOH=C10H3102K+C2H302K+H2 

The  oleates  of  the  alkaline  metals  are  soft,  soluble  soaps;  those 
of  the  earthy  metals  are  insoluble  in  water.  The  action  of  iodine 
and  of  bromine  upon  oleic  acid  is  utilized  in  the  analysis  of  fats  and 
oils.  At  the  ordinary  temperature  the  fatty  acids,  including  palmitic 
and  stearic,  are  not  affected  by  iodine,  but  the  double  bond  in  oleic 
acid  is  broken,  and  one  molecule  of  oleic  acid  combines  with  two 
atoms  of  iodine.  Under  like  conditions  each  molecule  of  linoleic  acid 
takes  up  four  atoms  of  iodine.  The  amount  of  iodine  which  a  given 
weight  of  a  fat  or  oil  can  combine  with  will  increase  with  its  tenure 
of  oleic,  or,  particularly,  of  linoleic  acid.  ' '  Hubl  's  iodine  number  " 
of  a  fat  or  oil  is  the  quantity  of  iodine  which  100  grams  of  the  sub- 
stance can  take  up  under  the  conditions  of  the  process  and  is  an 
important  factor  for  its  identification. 

Elaidic  Acid — CnH33.COOH — is  an  isomere  of  oleic  acid,  produced  from  it 
by  the  action  of  nitrous  acid.  It  is  a  crystalline  solid,  fusible  at  51°.  Its  for- 
mation is  utilized  to  distinguish  non-drying  from  drying  oils  (p.  282).  The 
former,  containing  oleic  acid,  solidify  when  acted  on  by  nitrous  acid;  the 
latter,  containing  linoleic  acid,  do  not. 

Olefine  dicarboxylic  Acids. — The  acids  of  this  series  contain  two  atoms  of 
hydrogen  less  than  the  corresponding  acids  of  the  oxalic  series,  and  they  con- 
sequently bear  the  same  relation  to  those  acids  that  the  acids  of  the  oleic  series 
bear  to  those  of  the  acetic  series. 

Esters  of  three  acids  having  the  composition  C2H2(COOH)2  are  known. 
The  free  acid  corresponding  to  one  of  these,  methylene  malonic  ester, 

CH2 :  C  S  QQQ  |  £2 jj5  j  ,  is  not  known.    The  other  two,  fumaric  and  maleic  acids, 

are  "space  isomerides  "  (p.  238).    Fumaric  acid  is  considered  to  have  the  axial 

H.C.OOH 
symmetric  structure:  ,  because  it  does  not  yield  an  anhydride, 

HOOC.C.H 

and  because,  on  oxidation,  it  yields  racemic  acid,  while  maleic  acid  has  the  plane 
symmetrical  structure,  because,  owing  to  the  closer  proximity  of  the  carboxyls, 
H.C.COOH  H.C.CO\ 

,  it  readily  forms  an  anhydride,  0,  and  because  on  oxidation 

H.C.COOH  H.C.CO/ 

it  yields  inactive,  or  meso-tartaric  acid  (see  p.  239  and  Fig.  18,  ibid.). 

Fumaric  acid  exists  free  in  many  plants,  notably  in  Iceland  moss.  Fumaric 
and  maleTc  acids  are  readily  converted  one  into  the  other  by  simple  heating, 


UNSATURATED   ALIPHATIC   COMPOUNDS  333 

and  the  two  are  produced  together  by  the  action  of  heat  upon  malic  acid,  or 
by  boiling  solutions  of  monobromo-succinic  acid. 

Fumaric  acid  crystallizes  in  small  prisms,  almost  insoluble  in  cold  water, 
which  sublimes  at  200°.  Male'ic  acid  fuses  at  130°,  and  boils  at  160°.  Both 
fumaric  and  male'ic  acids  are  converted  into  succinic  acid  by  nascent  hydrogen. 

Allyl  Oxide — Allylic  ether—  ( CH2 :  CH.CH2 )  20 — is  an  example  of  the  un- 
saturated  ethers.  It  exists  in  small  quantity  in  crude  essence  of  garlic,  and  is 
formed  by  the  action  of  allyl  iodide  upon  sodium-allyl  oxide.  It  is  a  colorless 
liquid,  having  the  odor  of  garlic,  insoluble  in  water,  boiling  at  82°.  Mixed 
ethers  are  also  known,  such  as  propargyl  ethyl  ether,  CH;C.CH2.O.CH2.CH8.- 


UNSATURATED  SULPHUR  AND  NITROGEN  COMPOUNDS. 

Allyl  Sulphide — (CH2:CH.CH2)2S — corresponding  to  the  oxide,  is  the  prin- 
cipal constituent  of  volatile  oil  of  garlic,  obtained  by  distilling  garlic  with 
water.  It  is  formed  by  the  action  of  alcoholic  solution  of  potassium  sulphide 
upon  allyl  iodide.  It  is  a  colorless  oil,  lighter  than  water,  soluble  in  alcohol 
and  in  ether,  boils  at  140°. 

Allyl  Isothiocyanate — Mustard  oil — S:C:N.CH2.CH:CH2 — is  the  chief  con- 
stituent of  volatile  oil  of  mustard,  and  of  radish  oil.  It  is  prepared  artificially 
by  distilling  allyl  bromide  or  iodide  with  potassium  or  silver  thiocyanate: 

S :  C :  N.  Ag-f-CH2LCH :  CH2=S :  C :  N.CH2.CH :  CHz-f  Agl 

It  does  not  exist  preformed  in  the  mustard  seeds,  but  is  produced  by  the  de- 
composition of  a  glucoside,  potassium  myronate,  in  the  presence  of  water  under 
the  influence  of  an  enzyme,  also  contained  in  the  seeds,  called  myrosin.  The 
action  takes  place  at  0°,  but  not  at  temperatures  above  40°.  The  activity  of 
myrosin  is  also  impaired  by  the  presence  of  acetic  acid  (vinegar).  The  pungent, 
rubefacient  and  vesicant  actions  of  mustard  are  due  to  mustard  oil. 

Pure  allyl  isothiocyanate  is  a  colorless  oil,  sp.  gr.  1.015  at  20°,  boils  at 
150°,  has  a  penetrating,  pungent  odor,  sparingly  soluble  in  water,  very  soluble  in 
alcohol  and  in  ether.  Exposed  to  air  it  gradually  turns  brownish-yellow,  and 
deposits  a  resinoid  material.  Heated  with  HC1  or  with  H2O,  it  is  decomposed 
into  carbon  dioxide,  hydrogen  sulphide  and  allyl-amine: 

S :  C :  N.CH2.CH :  CH2+2H20=C02-f  SH2+NH2.CH2.CH :  CH2 


334  TEXT-BOOK   OF   CHEMISTRY 


CLOSED  CHAIN,  AROMATIC  OR  CYCLIC  COMPOUNDS. 

These  compounds,  which  include  many  important  natural  prod- 
ucts, and  a  practically  unlimited  number  of  synthetic  compounds, 
differ  from  the  members  of  the  open  chain  series  in  that  they  contain 
a  group  of  more  than  two  atoms  united  together  by  exchange  of 
valences  in  such  a  manner  as  to  form  a  closed  chain,  or  ring,  or 
nucleus.  If  all  the  atoms  so  united  are  carbon  atoms  the  substance 
belongs  to  the  carbocyclic  class;  if  an  element  other  than  carbon 
enters  into  the  formation  of  the  ring  the  substance  is  heterocyclic. 

Some  closed  chain  compounds  are  produced  by  the  interaction 
of  two  open  chain  compounds,  as  in  the  formation  of  certain  diamines 
(p.  296)  and  compound  ureas  (p.  316).  Others,  such  as  the  lactides 
(p.  283),  lactones  (p.  283),  and  lactams  (p.  323),  are  produced 
by  internal  reaction  in  an  open  chain  molecule.  But  the  principal 
method  of  formation  of  closed  chain  compounds  is  by  polymerization. 
In  some  cases  this  takes  place  at  comparatively  low  temperatures,  as 
in  the  formation  of  trioxymethylene  from  formaldehyde  (p.  228),  and 
of  the  polymeric  thioaldehydes  and  their  sulphones  (p.  284). 

Among  the  instances  of  formation  of  cyclic  from  acyclic  com- 
pounds there  is  one  of  polymerization  at  a  high  temperature  which  is 
of  special  interest  as  bearing  upon  the  constitution  of  the  cyclic 
compounds.  The  central  figure  of  the  carbocyclic  compounds  is 
benzene,  C0H6,  which  is  obtained  principally  from  gas-tar.  Coal  gas 
contains  acetylene,  C2H2,  and  it  is  easy  to  conceive  that  one  or  two 
of  the  bonds  uniting  the  two  carbon  atoms  in  acetylene  may  be 
loosened  under  the  influence  of  heat,  and  that  a  molecule  of  benzene 
may  be  produced  by  fusion  of  three  molecules  of  acetylene :  3C2H2= 
C6H6.  The  product  so  obtained  is  neither  dipropargyl,  HC:C.CH2.- 
CH2.C;CH,  nor  dimethyl  diacetylene,  H3C.CiC.C:C.CH3,  but  another 
substance,  the  nature  of  whose  substituted  derivatives  indicates  that 
the  six  hydrogen  atoms  are  of  equal  value,  and  therefore  similarly 
attached  to  carbon  atoms;  and,  there  being  three  bisubstituted  deriva- 
tives (p.  337),  to  at  least  three  different  carbon  atoms.  These  con- 
ditions can  only  be  fulfilled  by  a  cyclic  structure  of  the  molecule  of 
benzene  and  its  derivatives  (p.  336).  Pyridine  also,  which  has  a 
prominence  among  the  heterocyclic  compounds  corresponding  to  that 
of  benzene  among  the  carbocyclic,  has  been  obtained  from  acetylene 
and  hydrocyanic  acid  by  a  fusion  very  similar  to  that  by  which 
acetylene  alone  forms  benzene:  2C2H2+HCN=C5H5N.  It  is  also 
formed  by  the  action  of  heat  upon  substances  containing  nitrogen 
as  well  as  carbon. 


CARBOCYCLIC    COMPOUNDS  335 


CARBOCYCLIC  COMPOUNDS. 

Carbocyclic  compounds  are  known  containing  from  three  to  seven 
carbon  atoms  in  a  ring.  Compounds  are  also  known  containing  a 
much  larger  number  of  carbon  atoms,  but  these  are  formed  by  fusion 
or  union  of  two  or  more  rings  of  six  carbon  atoms  or  less,  or  by  the 
attachment  of  an  open  chain  grouping  upon  a  closed  chain  one 
(p.  340).  The  hexacarbocyclic  compounds  are  far  more  numerous 
and  important  than  the  others. 

The  mononuclear  carbocyclic  hydrocarbons  have  algebraic  for- 
mula varying  from  CnH2»  to  CnH2«_6,  and  are  isomeric  with  the  un- 
saturated  open  chain  hydrocarbons  (p.  201).  Those  of  the  series 
CnR2n  are  known  as  polymethylenes,  being  considered  as  formed  by 
the  union  of  a  number  of  methylene  groups,  CH2.  Thus  hexahydro- 
benzene  is  hexamethylene,  CH2/^j'^\CH2.  But  the  chemical 

relations  of  the  polymethylenes  to  the  saturated  hydrocarbons  is 
closer  than  that  to  their  isomeres,  the  olefines,  because,  containing  no 
double  linkages,  they  cannot  be  modified  by  addition  without  disrup- 
tion of  the  ring.  So  long  as  the  cyclic  formation  is  maintained,  the 
polymethylenes  are  saturated  compounds,  as  are  the  paraffins.  For 
this  reason  their  "Geneva"  names  are  the  same  as  those  of  the  paraf- 
fins of  like  carbon  content,  to  which  is  prefixed  the  syllable  "  cycle," 
and  they  are  known  generically  as  cycloparaffins ;  or  the  symbol  R 
is  used  in  place  of  the  syllable  "cyclo."  The  hydrocarbons  of  the 
series  CnH2»-2,  isomeric  with  the  acetylenes  and  diolefines,  are  refer- 
able to  the  latter,  not  to  the  former,  as  they  cannot  contain  a  triple 
linkage  in  the  ring.  But,  containing  only  one  double  linkage,  they  are 
more  closely  related  to  the  olefines.  Therefore  tetrahydrobenzene, 
CH\CH2:^)CH2>  isomeric  with  hexadiene,  CH2:CH.CH2.CH2.CH> 
CH2,  containing  but  one  double  linkage,  is  cyclo-hexene,  or  R- 
hexene.  Similarly  dihydrobenzene,  CH/^2-^2^CH,  is  a  cyclo- 

diolefine :  R-hexadiene ;  and  benzene  a  cyclotriolefine :  R-hexatriene. 
The  cycloparaffins  are  formed  by  the  action  of  sodium  upon  the 
dibromoparaffins.     Thus  trimethylene  is  obtained  from  trimethylene 
bromide : 

/CH2 
CH2Br.CH2.CH2Br+Na2=CH2      I      +2NaBr 

\CH2 

Tri-,  tetra-,  penta-,  and  hepta-carbocyclic  hydrocarbons,  and 
their  numerous  derivatives,  notably  acids  and  ketones,  are  known. 
They  are  not  as  yet,  however,  of  medical  interest,  except  that  certain 
tetra-,  and  penta-compounds  are  among  the  decomposition  products 
of  certain  alkaloids. 


336  TEXT-BOOK   OF   CHEMISTRY 


HEXACARBOCYCLIC  COMPOUNDS—  AROMATIC 
SUBSTANCES. 

These  compounds,  which  are  very  numerous  and  important,  all 
contain  a  group  of  six  carbon  atoms,  to  which  are  attached  six,  eight, 
ten  or  twelve  univalents,  or  their  equivalent.  As  the  simplest  repre- 
sentative of  the  class  is  benzene,  C6H6,  and  as  all  of  these  bodies  may 
be  derived  from  benzene,  directly  or  indirectly,  and  yield  that  hydro- 
carbon on  decomposition,  the  aromatic  substances  may  be  considered 
as  derivatives  of  benzene.  This  being  the  case,  the  constitution  of 
benzene  itself  is  of  great  importance,  and  has  been  the  subject  of 
much  study.  Several  schematic  representations  of  the  structure  of 
the  benzene  molecule  have  been  suggested,  the  most  demonstrative 
of  which  are  the  hexagonal  form  of  Kekule,  the  prismatic  form  of 
Ladenburg,  and  the  diagonal  form  of  Claus  : 

H  H 

H  J,  _  J,  H 


A 


H— C        C— H 

J  L 


A 


H— C 


/ 


C 


C— H 


O— H 


Hexagonal.  Prismatic.  Diagonal. 

In  the  hexagonal  formula  the  carbon  atoms  exchange  one  and  two 
valences  alternately,  each  being  attached  to  two  others;  in  the  pris- 
matic form  each  carbon  atom  is  attached  to  three  others  by  single 
valences;  and  in  the  diagonal  form  the  hexagon  is  retained,  but,  in 
place  of  double  linkages,  a  central  linkage  between  all  the  carbon 
atoms  is  substituted.  All  of  these  formulas  represent  the  equivalence 
of  the  carbon  atoms,  and  the  constitution  of  isomeres  equally  well 
(see  below).  The  prismatic  formula  cannot  be  modified  to  represent 
a  constitution  of  the  additive  derivatives  of  benzene,  such  as  dihydro- 

benzene,  CH^g|'£f')CH,  and  tetrahydrobenzene,  CH{^^)CHr 
Neither  the  prismatic  nor  the  diagonal  formula  admits  double  link- 
ages between  carbon  atoms  in  the  ring.  That  these  exist  is  shown, 
however,  by  the  formation  of  the  additive  products  mentioned,  by  the 
formation  of  anhydrides  from  ortho-derivatives  only  (see  below),  and 
by  certain  physical  properties.  Moreover,  the  hexagonal  formula  ac- 


HEXACARBOCYCLIC    COMPOUNDS 


337 


cords  well  with  the  tetrahedral  representation  of  the  valences  of  the 
carbon  atom  (p.  239),  the  six  tetrahedra  being  alternately  united  by 
edges  and  apexes  in  benzene,  and  by  apexes  in  hexahydrobenzene. 
For  these  (and  other)  reasons,  chemists  have  very  generally  adopted 
the  hexagonal  expression,  although  it  still  leaves  something  to  be 
desired.  The  figure  of  a  hexagon  is  used  in  chemical  writings  to  rep- 
resent the  benzene  ring.  If  used  alone  it  represents  a  molecule  of 
benzene,  CGH6 ;  and  to  represent  the  products  of  substitution  the  sym- 
bols of  the  substituted  group  are  written  in  the  proper  position, 
thus: 

COOH 


Benzene. 


Benzole   acid. 


Dlhydrobenzene. 


—  CO 


Plithalic   anhydride. 


Isomerism  of  Benzene  Substitution  Products. — (1)  The  six 
atoms  of  hydrogen  in  benzene  are  of  equal  value.  There  exists  but 
one  mono-substituted  derivative  of  benzene  containing  any  given 
univalent:  one  chlorobenzene,  C6H5C1,  one  nitro-benzene,  C6H5(N02), 
one  amido-benzene,  C6H5(NH2),  one  benzoic  acid,  C6H5.COOH,  etc. 
Therefore,  benzene  is  symmetrical  in  structure,  and  its  hydrogen 
atoms  equal  each  other  in  value,  as  do  those  of  methane,  while  those 
of  pyridine  (p.  000)  are  not  all  of  like  value. 

2.  Any  hydrogen  atom  selected  in  the  benzene  ring  is  symmetri- 
cally placed  in  reference  to  two  pairs  of  hydrogen  atoms,  and  to  the 
sixth  hydrogen  atom  individually.  With  all  di-,  tri-,  and  tetra-substi- 
tuted  derivatives  of  benzene,  containing  like  substituted  univalents, 
there  are  three  isomeres.  Three  dichloro-,  three  trichloro-,  and  three 
tetrachloro-benzenes,  etc.,  and  in  no  instance  are  more  than  three 
known.  There  is  but  one  explanation  of  the  facts  mentioned  above, 
namely,  that  the  different  bi-,  tri-,  and  tetra-derivatives  are  pro- 
duced by  differences  in  the  relative  positions  of  the  substituted 
groups,  by  differences  in  "  orientation,"  as  among  the  aliphatic  com- 
pounds, the  several  oxyacids  are  "  place  isomeres  "  of  each  other 
(p.  260). 

The  hexagonal  formula  of  benzene  is  very  convenient 
for  showing  the  structure  of  the  several  isomeres.  For 
this  purpose  the  carbon  atoms  are  numbered,  beginning, 
for  convenience,  at  the  top  and  proceeding  clockwise. 

It  has  been  demonstrated  that  in  some  of  the  bisubsti- 
tuted  derivatives  the  two  substituted  groups  are  attached 
to  adjacent  carbon  atoms,  i.e.,  to  1-2,  2-3,  3-4,  4-5,  5-6,  or  6-1. 
Clearly  for  each  carbon  atom  there  is  a  pair  of  adjacent  positions,  as 


338 


TEXT-BOOK   OF    CHEMISTRY 


1-2  and  1-6,  2-1  and  2-3,  etc.,  which  are  equivalent  to  each  other.* 
In  other  bisubstituted  derivatives  it  may  be  shown  that  the  two 
substituted  groups  are  attached  to  carbon  atoms,  separated  from  each 
other  by  one  carbon  atom  on  one  side  and  by  three  on  the  other,  an 
arrangement  which  renders  the  hexagon  unsymmetrical.  Such  posi- 
tions are  1-3,  2-4,  3-5,  4-6,  5-1,  and  6-2.  Or,  for  each  carbon  atom 
there  is  a  pair  of  equivalent  unsymmetrical  positions,  as  1-3  and  1-5, 
etc.  There  remains  but  one  other  arrangement  possible,  the  sym- 
metrical, or  diagonal,  1-4,  2-5,  3-6.  With  the  tri-  and  tetra-substi- 
tuted  derivatives  there  are  also  three  possible  arrangements  :  the  adja- 
cent, vicinal,  or  consecutive,  as  1-2-3,  2-3-4  ;  1-2-3-4,  or  2-3-4-5  ; 
the  unsymmetrical,  as  1-2-4,  3-4-6;  1-2-3-5,  or  3-4-5-1;  and  the 
symmetrical,  as  1-3-5,  2-4-6;  1-2-4-5,  or  3-4-6-1.  Compounds  in 
which  the  substitution  is  adjacent  are  designated  as  ortho-com- 
pounds, or,  in  writing,  by  the  abbreviation  o-,  or  by  the  figures 
1-2,  etc.  Thus  C6H4(OH)2(1_2),  o-diphenol.  Unsymmetrical  com- 
pounds are  designated  as  meta-compounds,  or,  abbreviated,  m-,  or  by 


the  figures,  1-3,  etc.;  e.g.,  C6H3(Br) 


3(1.24)  , 


m-tribromobenzene.     Sym- 


metrical compounds  are  designated  as  para-compounds,  abbreviated 
p-,  or  1-4,  etc.:  e.g.,  C6H2(NH2)4(1.24^),  p-tetraamido-benzene.  Or, 
to  illustrate  by  the  formulae  of  the  di-  and  tetra-chlorobenzenes  : 


1-2-3-5 

Unsymmetrical. 
Meta. 


In  the  bisubstituted  derivatives  it  is  immaterial  whether  the  two 
substituted  groups  are  of  the  same  kind  or  different.  But  when,  in 
a  trisubstituted  derivative,  the  substituted  groups  are  not  the  same 


•  Note.  —  The  principal  objection  to  the  hexagonal  formula  of  benzene  (and  stated  by  K<-kule 
himself)  is  that  these  two  positions  are  not  entirely  equivalent,  as  in  the  position  1-2  (lie 
grouping  Is=C  —  C=,  while  in  1-6  It  is  —  C=C  —  ,  and  that  consequently  there  should  b«>  t\v«. 
ortho  derivatives,  while  but  one  Is  known.  The  student  is  referred  to  more  extended  works 
for  a  discussion  of  this  subject. 


HEXACARBOCYCLIC    COMPOUNDS 


339 


in  kind,  the  number  of  possible  isomeres  is  increased.  Thus  there 
are  six  possible  chloro-dibromobenzenes  (formulae  1  to  6  below),  of 
which  two  (1  and  2)  are  derived  from  orthodibromobenzene,  C6H4:- 
Br2  three  (3,  4,  and  5)  from  metadibromobenzene,  C6H4:Br 


2(1  3) 


1) 

and  one  (6)  from  paradibromobenzene,  C6H4Br2(1  4)  The  number  of 
possible  trisubstituted  derivatives  is  increased  to  ten  when  all  three 
substituted  groups  are  of  different  kind. 


Orthodibromo- 
metachloro. 


Orthodibromo- 
parachloro. 


Metadlbromo- 
orthochloro. 


OH 


(NO,) 


Metadibromo- 
allometachloro. 


Paradibroino- 
metachloro. 


In  naming  these  derivatives,  the  characterizing  group  of  the 
parent  substance  is  given  the  position  1  in  the  hexagon,  the  prefix 
"  ortho  "  is  applied  to  the  name  of  the  group  occupying  one  of  the 
ortho  positions  2  and  6,  "  meta  "  to  that  occupying  one  of  the  meta 
positions  3  and  5,  and  "  para  "  to  that  occupying  the  para  position  4. 
Thus  the  substance  having  the  formula  7  above  is  orthonitro-meta- 
bromo-phenol.  But  another  substance  is  known,  not  identical  with 
this,  having  the  formula  8  above,  in  which  the  nitro  group  occupies 
the  second  ortho  position,  6.  To  distinguish  substances  such  as 
these,  the  designation  "  allortho  "  is  given  to  the  position  6,  and  the 
designation  "  allometa  "  to  the  position  5.  Thus  the  substance  having 
the  formula  8  is  metabromo-allorthonitro-phenol.  When  formulae 
are  used  the  numerals  corresponding  to  the  position  of  substitution, 
enclosed  in  brackets,  are  placed  after  the  symbols.  Thus  7  is  writ- 
ten: C0H3(OH)(N02)[8]  Br[3J,  and  8:  C6H3(OH)Br|31  (N02)L6] 

Classification  of  Aromatic  Substances. — The  benzene  derivatives 
may  be  classified  into  five  classes : 

A.  Compounds  containing  a  single  benzene  nucleus,  unmodified 
except  by  substitution  for  hydrogen.  Monobenzenic  compounds.  In- 


340  TEXT-BOOK   OF    CHEMISTRY 

eludes  benzene  and  its  homologues,  and  the  phenols,  alcohols,  acids, 
etc.,  derived  from  them. 

B.  Compounds  containing  a  single  benzene  nucleus  in  which  one 
(or  more)  of  the  double  bonds  has  been  converted  into  a  single  one, 
thus  adding  two,  four,  or  six  valences  to  the  carbon  ring.    Monohy- 
drobenzenic  compounds.    Includes  the  cyclohexadienes,  cyclohexenes, 
and  cyclohexanes  (p.  335),  and  their  derivatives,  among  which  are 
the  terpenes  and  camphors. 

C.  Compounds  containing  two  (or  more)  benzene  nuclei,  or  ben- 
zene and  pentacarbocyclic  rings,  fused  together,  and  having  two  car- 
bon atoms  in  common.     Includes  indene,  fluorene,  naphthalene,  an- 
thracene, and  phenanthrene  and  their  derivatives.    Compounds  with 
condensed  nuclei. 

D.  Compounds  containing  two  (or  more)  benzene  rings,  directly 
united  by  loss  of  two  H  atoms.    Diphenyl  and  its  derivatives. 

E.  Compounds  containing  two  (or  more)  benzene  nuclei,  united 
by  aliphatic  groups.    Includes  di-  and  polyphenyl  paraffins,  olefines 
^and  acetylenes  and  their  derivatives. 

The  following  formulas  will  serve  to  indicate  the  differences  in 
constitution  of  the  several  classes: 

CH,  H2  H          H 

A  a  i   i 

//\  /\  //\  /\\ 

H—  C        C—  H  H2C        CH2  H—  C        C        C—  OH 

H—  C        C-H  H2C        CHa  H—  C        C        C—  H 

\\/  \/  \\/    \// 

C  C  C  C 

A  I  A   ^ 

(A)  (B)  (C) 

Methyl-benzene.  Hexahydrobenzene.  j8  Naphthol. 


HHHH  HH  HH 

u     <u 


/\/\  /       V/  I"     /.-      \ 

c—  c—  c 


(NH,).C  C.C  C.(N.Ha)       H—  C  C—  C—  C  C—  H 

\\          //       \\          //  \\          //  \\          // 

C—  C  C—  C  C—  C  H  C—  C 


(D)  (E) 

Pa  —  Dlainido-dlpbenyl  Dipbenyl-methane. 


MONOBENZENIC    COMPOUNDS  341 

A.    MONOBENZENIC  COMPOUNDS. 
HYDROCARBONS. 

Benzene — Benzol — C6H6 — (not  to  be  confounded  with  benzine, 
a  mixture  of  hydrocarbons  of  the  series  CnH2n-i-2,  obtained  from 
petroleum)  does  not  exist  in  nature.  It  is  obtained,  pure,  by  decom- 
posing benzoic  acid  by  heating  with  slaked  lime: 

C6H5COOH+CaH202=CaC03+C6H6+H20. 

It  is  produced  in  the  distillation  of  coal,  and  exists  in  coal  tar, 
from  which  it  is  obtained  for  use  in  the  arts. 

Coal  tar,  or  gas  tar,  is  a  very  complex  mixture,  containing  forty 
or  fifty  substances — hydrocarbons,  phenols  and  bases — and  is  the 
crude  material  from  which  many  important  substances  are  obtained. 
In  working  it,  it  is  first  distilled,  four  fractions  being  collected: 
(1)  Light  oil,  distilling  below  150°;  (2)  carbolic  oil,  or  middle  oil, 
distilling  below  230°.  Contains  phenols  and  naphthalene.  (3) 
Heavy  oil,  or  creosote  oil,  distilling  below  270°.  Furnishes  naphtha- 
lene. (4)  Green  oil,  or  anthracene  oil,  distilling  above  270°.  Con- 
tains anthracene  and  other  solid  hydrocarbons.  The  residue  in  the 
still  is  pitch.  The  light  oil  contains  benzene,  toluene  and  xylene, 
with  some  thiophene,  phenols,  pyridine,  and  heavy  oils.  It  is  further 
purified  to  yield  various  grades  of  commercial  "benzol,"  the  best 
of  which  contains  about  70  per  cent,  of  benzene,  and  24  per  cent,  of 
toluene,  with  some  xylene,  cumene  and  thiophene. 

Pure  benzene  is  a  colorless  liquid,  having  an  ethereal  odor,  crystal- 
lizing at  5.4°,  boiling  at  80.5°,  sp.  gr.  0.86  at  15°,  immiscible  with 
water,  mixing  with  alcohol  and  ether.  It  dissolves  I,  S,  P,  resins, 
caoutchouc,  guttapercha,  fats  and  many  alkaloids.  It  is  inflammable, 
and  burns  with  a  smoky  flame. 

Benzene  unites  directly  with  Cl  or  Br  to  form  products  of  addition 
or  of  substitution.  Free  Cl  acts  only  slowly  upon  benzene  alone,  but 
the  action  is  much  accelerated  by  the  presence  of  certain  chlorides, 
particularly  FeCl3.  The  corresponding  I  derivatives  can  only  be 
obtained  indirectly.  Sulphuric  acid  combines  with  it  to  form  benzene 
sulphonic  acid,  C6H5.S03H.  Nitric  acid  converts  it  into  nitre-ben- 
zene, C6H5.N02,  or,  if  fuming  HN03  is  used  and  the  mixture  boiled, 
into  a  mixture  of  the  three  dinitro-benzenes,  C6H4(N02)2.  It  is  re- 
duced to  hexahydrobenzene  by  hydriodic  acid. 

Homologues  of  Benzene. — These  may  be  considered  as  alkyl-benzenes, 
formed  by  the  substitution  of  alkyl  groups  for  an  equivalent  number  of  hydrogen 
atoms  in  benzene.  The  usual  general  method  of  their  formation  indicates  the 
constitution:  they  are  obtained  by  treating  a  mixture  of  bromobenzene,  ether, 


342  TEXT-BOOK   OF    CHEMISTRY 

and  the  bromide  or  iodide  of  the  corresponding  alcoholic  radical  with  sodium. 
Thus  mono-bromo-benzene  and  methyl  bromide  yield  methyl-benzene,  or  toluene: 

CflH5Br-fCH3Br-(-Na2=:2NaBr-fC6H5.CH3 

They  are  also  formed  by  the  action  of  the  alkyl  chlorides  upon  the  inferior 
homologues  in  presence  of  A1C13,  or  of  ZnCl2,  or  FeCl3.  Thus  benzene  and 
methyl  chloride  form  toluene: 

C6H6-fCH3Cl=C6H5.CH8-fHCl 

This  is  a  general  method  frequently  used  for  the  reduction  of  alkyls  into 
aromatic  compounds,  and  probably  depends  upon  the  formation  of  intermediate 
organo-metallic  compounds  (p.  288).  There  are  numerous  other  methods  for 
their  production.  The  superior  homologues  of  benzene  include  many  isomeres. 
Thus  there  are: 

1— C7H8,  i.e.,  C6H5(CH8) -Methyl-benzene, 

4 — C8H10,  i.e.,  three  C6H4  ( CH3 )  2-o-,  m-,  and  p-Dimethyl-benzenes, 

C8H5  ( C2H5 )  -Ethyl-benzene, 
8 — C9H12,     i.e.,  three  C6H3(CH8)8-o-,   m-,  and  p-Trimethyl-benzenes, 

three  C6H4  ( CH3 )  (C2H5)-o-,m-,  and  p-Methyl-ethyl  benzenes, 
C6H5  ( C8H7 )  -Propyl -benzene, 
C6H5  ( C3H7 )  -Isopropyl-benzene, 

1 9-r-C10HM  i.e.,  three  CflH2(CH8)4-o-,  m-,  and  p-Tetramethyl  benzenes, 
three  CaH4  ( C2HB )  2-o-,  m-,  and  p-Diethyl-benzenes, 
three  CflH3  ( CH3 )  2  ( C2H5 ) -o-,  m-,  and  p-Dimethylethyl-benzenes, 
three  C6H4  ( CH3 )( C3HT ) -o-,  m-,  and  p-Methylpropyl-benzenes, 
three  CaH4  ( CH8 )  (C3H7)-o-,  m-,   and  p-Methylisopropyl-benzenes, 
four    C6H5(C4H9) -Butyl-benzenes. 

The  homologues  of  benzene  are  acted  upon  by  reagents  in  the  same  manner 
as  benzene  itself.  In  addition,  the  lateral  chain  may  be  acted  upon.  Benzene 
is  not  acted  upon  notably  by  oxidizing  agents  unless  they  be  sufficiently  power- 
ful to  disrupt  the  molecule.  But  oxidants  such  as  dilute  nitric  acid,  or  the 
chromic  mixture,  oxidize  the  lateral  chain  in  the  homologues  of  benzene,  with 
formation  of  carboxylic  acids.  Thus  methyl-benzene,  CeH5.CH3,  yield  benzoic 
acid,  C6HB.COOH. 

Toluene — Toluol— Methyl-benzene — C6H5.CH8 — exists  in  the  products  of 
distillation  of  coal,  wood,  etc.,  and  is  a  constituent  of  commercial  benzene.  It  is 
formed  synthetically  by  the  general  methods  given  above;  or  may  be  obtained 
pure  by  decomposition  of  one  of  the  toluic  acids  by  lime. 

It  is  a  colorless  liquid,  boils  at  110.3°,  does  not  solidify  at  — 20°,  sp.  gr. 
0.872  at  15°,  does  not  mix  with  water,  but  mixes  with  alcohol,  ether  and  carbon 
bisulphide. 

Xylenes — Xylols — C8H10. — Four  isomeres  are  possible  and  are  known: 
ethyl-benzene,  CaH8.C2H6— and  ortho-  (1—2),  meta-  (1—3),  para-  (1 — 4), 
dimethyl-benzenes,  C6H4(CH8)2.  Ethylbenzene  is  a  colorless  oil,  b.  p.  134°, 
obtained  by  fractional  distillation  of  animal  oil.  The  three  dimethyl  benzenes 
exist  in  coal  tar  and  in  the  commercial  xylene,  b.  p.  139°,  70%  consisting  of  meta- 
xylene,  and  paraxylene  being  present  in  very  small  amount.  Mesitylene, 
formed  by  distilling  acetone  or  allylene  with  H2SO4,  is  p-trimethylbenzene. 
Cymene,  a  liquid  having  a  pleasant  odor,  present  in  several  ethereal  oils,  is 
p-methylisopropyl-benzene.  It  is  formed  by  the  action  of  methyl  iodide  upon 
p-bromo  isopropyl-benzene  in  presence  of  Na. 


BENZENIC   OXYGEN   COMPOUNDS  343 


HALOID  DERIVATIVES. 

By  the  substitution  of  atoms  of  Cl,  Br  and  I  for  the  hydrogen  of 
the  principal  and  lateral  chains  in  benzene  and  its  superior  homo- 
logues,  a  great  number  of  substances  are  obtained,  many  of  them 
forming  isomeric  groups. 

The  chlorobenzenes  are:  Monochlorobenzene :  C6H5C1,  liquid,  b. 
p.  132°,  sp.  gr.  at  0°-1.128°;  obtained  by  the  action  of  Cl  upon 
C6H6  in  the  cold,  in  presence  of  a  little  I. 

Orthodichlorobenzene :  C6H4C12  a.2) ,  liquid,  b.  p.  179°,  sp.  gr. 
1.328  at  0°;  obtained  by  the  action  of  Cl  upon  C6H6. 

Metadichlorobenzene :  C6H4C12  (i.3) ,  liquid,  b.  p.  172°,  sp.  gr. 
1.307  at  0°;  obtained  indirectly. 

Paradichlorobenzene :  C6H/}12  (14) ,  crystalline,  f.  p.  56.4°,  b.  p. 
170  °,  is  the  principal  product  of  the  action  of  Cl  on  C6H6  in  presence 
of  I. 

Metatrichlorobenzene :  C6H3C13  a2.4),  crystals,  f.  p.  17°,  b.  p.  213°. 

Paratrichlorozenzene :  C6H3C13  a-j«),  crystals,  f.  p.  63.4°,  b.  p. 
208°. 

Metatetrachlorobenzene :  C6H2C14  a  2-3-5),  crystals,  f.  p.  50°,  b.  p. 
246°. 

Paratetrachlorobenzene :  C6H2Cl4(i24^),  crystals,  f.  p.  137°,  b.  p. 
245°. 

Benzyl  chloride — C6H5CH2C1 — is  an  example  of  the  substitution 
of  a  halogen  in  the  lateral  chain  of  a  superior  homologue  of  benzene. 
It  is  obtained  by  the  action  of  chlorine  upon  boiling  toluene;  or  of 
PC15  on  benzylic  alcohol.  It  is  a  colorless  liquid,  boils  at  176°,  and 
gives  off  pungent  vapors  which  excite  the  lachrymal  secretion.  It 
is  readily  oxidized  to  benzoic  aldehyde  or  benzoic  acid,  and  serves 
for  the  introduction  of  the  radical  benzyl  into  other  molecules.  The 
radical  of  benzylic  alcohol  (C6H5.CH2)  is  called  benzyl;  that  of 
benzoic  acid,  (C6H5.CO),  benzoyl.  The  groups  C6H5,  called  phenyl, 
and  C6H4,  called  phenylene,  behave  as  radicals,  corresponding  to  the 
alkyls  and  alkylenes  respectively. 


BENZENIC  OXYGEN  COMPOUNDS. 

The  derivatives  of  benzene  containing  oxygen  include,  besides 
alcohols,  aldehydes,  ketones,  acids,  ethers,  and  anhydrides,  cor- 
responding to  those  of  the  open  chain  series,  a  class  of  hydroxides, 
the  phenols,  of  which  there  are  no  aliphatic  prototypes. 


344  TEXT-BOOK   OF   CHEMISTRY 


PHENOLS. 

In  the  phenols  the  hydroxyl  is  substituted  for  the  hydrogen  of  the 
benzene  ring,  while  in  the  alcohols  the  substitution  occurs  in  a  lateral 
chain.  Thus  phenol  is  C6H5.OH;  benzylic  alcohol,  C6H5.CH2OH. 
All  six  of  the  hydrogen  atoms  of  benzene  may  be  thus  replaced  to 
form  monohydric  phenols,  dihydric  phenols,  etc. 

In  their  properties  the  phenols  differ  from  the  alcohols  by  more 
nearly  approaching  the  character  of  the  acids.  On  oxidation  they  do 
not  furnish  aldehydes  or  acids;  they  do  not  divide  into  water  and 
hydrocarbon  under  the  influence  of  dehydrating  agents  ;  they  do  not 
react  with  acids  to  form  esters  ;  they  combine  directly  with  Cl  and  Br 
to  form  products  of  substitution  ;  they  form  with  the  metallic  elements 
compounds  more  stable  than  similar  compounds  of  the  true  alcohols. 

The  tertiary  aliphatic  alcohols  are  those  which  most  closely  resem- 
ble the  phenols.  They  both  contain  the  group  C.OH,  triply  linked  to 

ri   p\  _  TTC'X. 

other  carbon  atoms:   (HgC3)2//C.OH,  and  ^HC//C-CH>  an(^  they  also 


resemble  each  other  in  that  each  is  only  slowly  and  imperfectly  esteri- 
fied  when  heated  to  150°  with  acetic  acid.  But,  while  the  tertiary 
alcohols  are  readily  attacked  by  phosphorus  pentachloride,  with  for- 
mation of  alkyl  chlorides: 

(  CH3)  3!C.OH+PC15=  (  CH3)  3:-C.Cl+POCl3+HCl 
that    reagent    displaces    the    hydroxyl    of    the    phenols    only    im- 
perfectly, or  not  at  all.    The  products  of  the  reaction  with  phenol  are 
either  phenyl  phosphoric  tetrachloride  : 

C6H5.OH+PC15:=C6H5.OPC14+HC1 

or  a  mixture  of  monochlorobenzene  with  either  diphenyl  phos- 
phoric acid  : 

4C6H5.OH+PC15=2C6H5C1+P04H(C6H5)2+3HC1, 
or  triphenyl  phosphate: 

4C6H5.OH+PC15=C6H5C1+P04  (  C6H5)  3+4HCl 
The  latter   alone    is   produced   by   the   action   of   phosphorus    oxy- 
chloride  on  phenol: 

3C6H5.OH-f  POC13=P04  (  C6H5)  3+3HCl 

The  phenols  occur  in  nature  in  small  quantities  only  ;  some  in  the 
vegetable  world,  and  some  in  combination  as  ester  sulphuric  acid  in 
the  urine.  They  are  mostly  products  of  distillation  of  wood,  coal, 
etc. 

MONOATOMIC—  MONOHYDRIC  PHENOLS. 

The  monoatomic  phenols  are  produced:  (1)  by  fusing  the  cor- 
responding sulphonic  acids  with  caustic  alkali: 

C6H5.S03K+KOH=C6H5.OH+K2S03 


PHENOLS  345 

(2)  By  decomposition  of  the  diazo-compounds  by  boiling  with 
water : 

C6H5.N:N.HS04+H20=C6H5.OH+N2+H2SO, 

(3)  The  higher  phenols  are  produced  by  heating  phenol  with 
ZnCl2  and  the  alcohols,  a  phenolic  ether  being  also  formed.     Thus 
phenol  and  methylic  alcohol  yield  cresol  and  methyl-phenyl  ether : 

2C6H5.OH+2H.CH2OH=C6H4.OH.CH3+C6H5.O.CH3+2H20 

(4)  The  phenyl  magnesium  halides  are  oxidized  by  passing  air 
through  their  ethereal  solutions  with  the  formation  of  compounds  of 
this  type:  R.O.Mg.X,  which  when  hydrolyzed  yield  phenols: 

C6H5.O.Mg.Br+H20=C6H5OH+HO.Mg.Br. 

The  phenols  are  reduced  to  hydrocarbons  by  heating  with  zinc 
dust.  Their  ring-hydrogen  is  readily  replaceable  by  other  elements 
or  groups  to  form  haloid,  nitro,  amido  derivatives,  etc.  Their  hy- 
droxyl  hydrogen  is  also  readily  replaceable  by  alkyls  to  produce 
ethers,  by  Na,  K,  and  Ca  to  produce  phenates,  and  by  acidyls  to  pro- 
duce phenyl  esters.  The  phenols  combine  with  the  diazo-compounds 
to  produce  azo-  and  diazo  dyes,  and  with  phthalic  acid  to  produce 
phthalems. 

Phenol — Benzophenol — Phenyl  hydroxide — Phenic  acid — Car- 
bolic acid — C6H5.OH — exists  in  considerable  quantity  in  coal-  and 
wood-tar,  and  in  small  quantity  in  castoreum  and,  in  combination,  in 
the  urine.  It  is  produced  in  the  intestine. 

It  is  formed:  (1)  by  fusing  sodium-phenyl  sulphide  with  excess 
of  alkali: 

C6H5NaS+NaOH=C6H5.OH+Na2S 

(2)  By  heating  phenyl  iodide  and  potassium  hydroxide  at  320°: 

C6H5I+KOH=CGH5.OH+KI 

(3)  By  heating  together  salicylic  acid  and  quicklime: 
C6H4.OH.COOH+Ca(OH)2=C6H5.OH+CaC03+H20 

(4)  By  total  synthesis  from  acetylene,  through  benzene,  and  its 
sulphonic  acid. 

(5)  By  decomposition  of  the  phenylic  esters  by  alkalies.     Thus 
salol  yields  phenol  and  salicylic  acid: 

C6H4.OH.COO(C6H5)+KOH=C6H5.OH+C6H4.OH.COOK 

(6)  By  dry  distillation  of  benzoin. 

"  Synthetic  phenol,"  prepared  by  method  (4),  is  now  manu- 
factured. "Carbolic  acid"  is  obtained  from  the  "middle  oil"  of  gas 
tar  (p.  341).  It  is  purified  by  conversion  into  potassium  phenate, 
C,.H5.OK,  which  is  crystallized,  decomposed  by  HC1,  and  the  liberated 
phenol  recrystallized  and  distilled. 


346  TEXT-BOOK   OF   CHEMISTRY 

Phenol  is  extensively  used,  not  only  as  an  antiseptic,  but  also  in 
the  manufacture  of  numerous  derivatives,  including  medicinal  com- 
pounds, dyes  and  explosives. 

Phenol  crystallizes  in  long,  colorless  needles,  fuses  at  43°,  boils 
at  183°,  sp.  gr.  1.084  at  0°,  has  a  characteristic  odor,  and  an  acrid, 
burning  taste,  soluble  in  15  parts  of  water  at  20°,  very  soluble  in 
alcohol  and  in  ether,  neutral  in  reaction.  It  may  be  distilled  without 
decomposition. 

Its  vapor  is  reduced  to  benzene  by  heating  with  Zn.  It  combines 
with  H2S04  to  form  o-,  and  p-phenol  sulphonic  acids.  With  HN03  it 
forms  2-4-6-trinitrophenol.  Heated  with  sulphuric  and  oxalic  or 
arsenic  acid,  it  yields  several  triphenyl-methane  dyes,  among  which 
are  corallin,  rosolic  acid,  peonin,  azulin,  aurin,  and  phenicin. 

Analytical  Characters — (1)  Its  peculiar  odor.  (2)  Mix  with  one 
quarter  volume  of  NH4OH ;  add  two  drops  of  sodium  hypochlorite 
solution,  and  warm:  a  blue  or  green  color.  Add  HC1  to  acid  reac- 
tion: turns  red.  (3)  Add  two  drops  of  the  liquid  to  a  little  HC1, 
and  then  a  drop  of  HN03:  a  purple  red  color.  (4)  Boil  with  HN03 
so  long  as  red  fumes  are  given  off;  neutralize  with  KOH:  a  yellow, 
crystalline  precipitate.  (5)  Heat  with  Millon's  reagent:  a  yellow 
ppt,  forming  a  red  solution  in  HN03.  (6)  With  solution  of  FeS04:  a 
lilac  color.  (7)  Add  excess  of  bromine  water:  a  yellowish-white  pre- 
cipitate. This  compound,  tribromophenol,  C6H2Br3OH,  is  the  form 
in  which  phenol  is  quantitatively  determined;  100  parts  of  it  cor- 
respond to  29.8  parts  of  phenol.  (8)  Moisten  a  pine  shaving  with  the 
liquid,  then  with  HC1,  to  which  a  trace  of  KC103  has  been  added  im- 
mediately before  use,  and  expose  to  sunlight :  a  fine  blue  color.  The 
test  should  be  tried  also  with  a  solution  of  phenol,  and  with  the 
acid  alone,  as  only  certain  varieties  of  pine  are  suitable. 

Toxicology. — Carbolic  acid  is  an  active  poison  and  corrosive.  It  has 
caused  death  in  a  dose  of  1.5  gram.  The  average  duration  of  fatal  cases  is  2-8 
hours.  Death  may  occur  in  3-5  minutes  from  collapse.  It  causes  a  burning 
sensation,  soon  followed  by  intense  pain  and  cauterization  of  all  parts  with 
which  it  comes  in  contact.  The  stain  which  it  produces  is  at  first  white,  after 
a  few  minutes;  later  it  turns  darker  and,  when  the  eschar  separates,  a  brown 
stain  remains,  which  persists  for  many  days.  Vomiting  usually  occurs,  the 
vomited  matters,  as  well  as  the  breath,  having  the  odor  of  carbolic  acid.  The 
patient  soon  becomes  unconscious,  and  death  is  from  collapse  or  in  coma. 
The  urine,  normal  in  color  when  first  voided,  soon  becomes  olive-green,  brown, 
or  even  black  in  color.  The  treatment  consists  in  administration  of  albumin, 
saccharated  lime,  sodium  sulphate,  or  strong  alcohol,  followed  by  lavage. 

Phenates. — Carbolates. — The  hydroxyl  hydrogen  of  phenol  is  re- 
placeable by  certain  metals  and  by  alkyls  to  form  phenates  and 
phenyl  ethers.  When  phenol  and  KOH  are  heated  together,  potas- 
sium phenate,  C6H5OK,  is  formed.  This,  when  treated  in  alcoholic 
solution  with  HgCl2,  produces  mercuric  phenate,  (C6H50)2Hg,  a 
yellow,  crystalline  solid  which  has  been  used  in  medicine. 


PHENOLS  347 

Phenol  Esters. — The  H  of  the  OH  of  phenol  is  replaceable  by 
either  alkyls  or  acidyls.  With  the  former  phenol  plays  the  part  of  an 
acid,  and  therefore  the  resulting  compounds  are  the  phenol  esters, 
corresponding  to  the  metallic  phenates.  But,  although  phenol  is  not 
an  alcohol,  the  radical  phenyl  (C6H5)'  of  which  it  is  the  hydroxide,  is 
in  all  respects  equivalent  to  the  alkyls,  of  which  the  monohydric  alco- 
hols are  the  hydroxides.  Therefore  the  phenol  esters,  such  as  C6H5.- 
O.CH3,  are  also  the  phenyl  ethers  (p.  360).  The  phenyl  esters,  on  the 
other  hand,  may  be  considered  as  derivable  from  phenol  by  substitu- 
tion of  acidyls  for  hydroxyl  hydrogen:  C6H5.0.(OC.CH3),  or  as 
derivable  from  the  acids  by  substitution  of  phenyl  for  carboxyl  hydro- 
gen: CH3.COO(C6H5).  The  phenyl  esters  are  formed  by  the  action 
of  the  acidyl  chlorides  upon  the  phenols,  or  upon  their  metallic 
derivatives : 

C6Hn.OH+CH3.COCl=CH3.C02.C6H5+HCl,  or 
C6H5.OK+CH3.COC1=CH3.C02.C6H5+KC1 

as  the  aliphatic  esters  are  formed  by  the  action  of  acidyl  halides  upon 
the  alcohols  or  upon  the  alcoholates. 

Cresols— Cresylols — Cresylic  acids — Benzylic  or  cresylic  phe- 
nols— C6H4<^Qg3 — 108. — Of  the  three  possible  compounds,  two,  the 

para  and  ortho,  accompany  phenol  in  coal-tar,  from  which  they  may 
be  separated  by  fractional  distillation.  They  are  more  readily  ob- 
tained pure  from  toluene.  Creolin — an  antiseptic  less  poisonous  than 
phenol,  consists  chiefly  of  cresols.  Lysol  is  impure  paracresol,  mixed 
with  fat  and  saponified. 

Creosote — Creosotum  (U.  S.  P.) — is  a  complex  mixture  contain- 
ing phenol,  cresol,  creasol,  C8H1002,  guaiacol,  C7H802  (see  pyro- 
catechol),  and  other  substances,  obtained  from  wood-tar,  and  formerly 
extensively  used  as  an  antiseptic.  It  is  an  oily  liquid,  colorless  when 
freshly  prepared,  but  becoming  brownish  on  exposure  to  light.  It 
has  a  burning  taste  and  a  strong,  peculiar  odor.  It  boils  at  203°, 
and  does  not  solidify  at  — 27°. 

Xenols — Xylenols. — Theoretically  there  are  six  possible  xenols  which  are 
dimethyl  phenols,  C6H3  ( CH3 )  2OH ;  two  derivable  from  orthoxylene,  three  from 
metaxylene  and  one  from  paraxylene.  They  have  all  been  produced  synthetically. 
There  are  also  three  possible  xenols  which  are  ethyl  phenols,  C6H4  ( C2H5 )  OH. 

Thymol — 3-Methyl-6-isopropyl  phenol — Cymylic  phenol — C6H3(OH)(1)- 
(CH3)(3)  (C3H7)(6), — exists,  accompanying  cymene  and  thymene,  C10HJ6,  in  essence 
of  thyme,  from  which  it  is  obtained.  It  is  also  prepared  synthetically  from 
cuminic  aldehyde,  C6H4(CHO)(i)  (C3H7)  r4). 

It  crystallizes  in  large,  transparent,  rhombohedral  tables;  has  a  peppery 
taste,  and  an  agreeable,  aromatic  odor.  It  fuses  at  44°,  and  boils  at  230°; 
is  sparingly  soluble  in  water,  very  soluble  in  alcohol  and  ether.  With  the 
alkalies  it  forms  definite  compounds,  which  are  very  soluble  in  water.  Its 
reactions  are  very  similar  to  those  of  phenol. 

Thymol  is  an  excellent  deodorizing  and  antiseptic  agent,  possessing  the 
advantage  over  phenol  of  having  itself  a  pleasant  odor. 


348  TEXT-BOOK   OF   CHEMISTRY 

Aristol  is  diiodo-thymol,  a  dibenzenic  compound,  produced  by  the  action  of 
a  solution  of  I  in  KI  upon  an  aqueous  solution  of  thymol  in  the  presence  of 
KOH.  It  is  an  inodorous,  yellowish-red  powder,  insoluble  in  H2O,  very  spar- 
ingly soluble  in  alcohol,  readily  soluble  in  ether  and  in  chloroform.  It  is 
decomposed  by  heat  and  by  light  and  is  said  to  be  a  non-poisonous  antiseptic. 

Carvacrol — 2-Methyl-5-isopropyl  phenol— C8H3  ( OH )  a)  ( CH3 )  (2)  ( C3H7 )  (5)_ 
an  isomere  of  thymol,  exists  in  many  essential  oils,  and  is  obtained  by  the 
action  of  iodine  upon  camphor;  by  the  action  of  potash  in  fusion  upon  cymene 
sulphonic  acid,  C10H13SO3H;  or  by  a  transposition  of  the  atoms  of  another 
isomere,  carvol,  which  exists  in  caraway  oil.  It  is  an  oil,  boiling  at  233°-235°. 
Heated  with  P2O6,  it  yields  orthocresol. 

SUBSTITUTED  PHENOLS. 

Phenol  is  a  monosubstituted  derivative,  and  hence  still  contains 
five  H  atoms  which  may  be  replaced  by  other  elements  or  radicals,  to 
produce  di-  or  tri-  or  poly-substituted  derivatives  of  benzene,  which 
will  be  ortho,  meta  or  para,,  etc.,  according  to  the  relations  of  the 
introduced  groups  to  the  OH,  already  existing  in  phenol,  or  to  the 
C«H2n  +  i  and  OH  groups  in  its  superior  homologues. 

Chlorophenols. — The  three  monochlorinated  compounds  are  ob- 
tainable from  the  corresponding  chloranilines.  Orthochlorophenol 
(1 — 2)  is  a  colorless  liquid,  boils  at  175°-176°,  converted  into  pyro- 
catechol  by  KOH.  Metachlorophenol  (1 — 3)  is  a  liquid,  boiling  at 
214°.  KOH  converts  it  into  resorcinol.  Parachlorophenol  (1 — 4)  is 
a  crystalline  solid,  fusible  at  37°,  converted  into  quinol  by  fusion 
with  KOH.  Di-,  tri-,  and  penta-chlorophenols  are  also  known. 

Bromophenols  correspond  in  method  of  formation  and  properties 
with  the  Cl  derivatives.  2-4-6  Tribromophenol — C6H2.OH.Br3 — is 
the  precipitate  formed  on  adding  bromine  water  to  phenol  solution. 
It  forms  white  crystals,  fusing  at  92°,  insoluble  in  water,  soluble  in 
alcohol  and  ether.  It  has  been  used  as  an  antiseptic  in  diphtheria 
under  the  name  Bromol. 

lodophenols  are  formed  by  the  action  of  iodine  and  K2S  upon 
phenol  in  the  presence  of  excess  of  alkali,  or  from  the  corresponding 
amidophenols.  Like  the  chlorine  and  bromine  derivatives,  they  yield 
the  corresponding  diphenol  by  the  action  of  KOH  in  fusion.  A  tri- 
iodophenol,  formed  by  the  action  of  solution  of  I  in  K2S  upon  an 
alkaline  solution  of  phenol,  has  been  proposed  as  a  substitute  for 
iodoform  under  the  name  annidalin. 

For  nitro-  and  amido-phenols,  see  pp.  369,  373. 

DIATOMIC,  OR  DIHYDRIC  PHENOLS. 

Diatomic  phenols  are  derived  from  the  benzenic  hydrocarbons  by 
the  substitution  of  two  (OH)  groups  for  two  atoms  of  hydrogen. 
In  obedience  to  the  laws  of  substitution  already  discussed,  three 
such  compounds  exist,  corresponding  to  each  hydrocarbon. 


PHENOLS  349 

Pyrocatechol — Pyrocatechin — Oxyphenic  add — Or  ttiodioxy -ben- 
zene— C6H4(OH)2  d-2)  is  obtained  from  catechin  or  from  morintannic 
acid  by  dry  distillation;  also  by  the  action  of  KOH  on  orthochlor- 
or  orthoiodo-phenol,  or  by  decomposing  its  methyl  ether,  guaiacol, 
by  HI  at  200°.  It  crystallizes  in  short,  square  prisms;  fuses  at  104°, 
and  boils  at  245.5°.  Readily  soluble  in  water,  alcohol,  and  ether. 
Its  aqueous  solution  gives  a  dark  green  color  with  FeCl3  solution, 
changing  to  violet  on  addition  of  NH4OH,  NaHC03,  or  tartaric  acid. 
Its  acid  sulphuric  ester  exists  in  the  urine. 

Monomethy  1-pyrocatechuic  Ether  —  Guaiacol  —  C6H4.OH. 
(OCH3)(2) — exists  in  beech-wood  tar,  from  which  an  impure  (60- 
90%)  guaiacol  is  obtained  as  a  yellowish  liquid,  sp.  gr.  1.133,  boiling 
at  206°-207°,  by  distillation.  Pure  guaiacol  is  obtained  from  this  by 
crystallization  at  low  temperature;  by  heating  pyrocatechol  with 
potassium-methyl  sulphate  and  KOH;  also  from  vanillin,  and  from 
veratrol.  It  is  a  crystalline  solid,  fuses  at  33°,  boils  at  205°,  soluble 
in  50  parts  of  water.  Guaiacol  has  been  used  in  the  treatment  of 
phthisis  both  on  account  of  its  germicidal  action,  and  upon  the  theory 
that  it  forms  compounds  with  the  toxalbumins,  which  are  readily 
eliminated.  It  is  also  used  in  numerous  forms  of  combination:  in 
its  carbonic  esters,  as  styracol=cinnamyl-guaiacol,  as  benzosol= 
benzoyl-guaiacol,  as  thiocol=guaiacol-potassium  sulphonate,  and  in 
combination  with  salicylic  acid. 

Dimethyl-pyrocatechuic  Ether— Veratrol— C6H4 ( OCH3)  2 (1.2)  —is 
an  oil,  crystallizing  at  15°,  formed  by  distilling  veratric  acid,  or  by 
acting  upon  the  potassium  salt  of  guaiacol  with  methyl  iodide. 

Resorcinol — Resorcin — Metadioxy -benzene — C6H4(OH)2(1  ?),  is  ob- 
tained by  the  action  of  fused  KOE  on  metachlor-,  or  iodophenol. 
It  is  also  prepared  by  dry  distillation  of  extract  of  Brazil  wood. 

It  forms  short,  thick,  colorless  and  odorless,  rhombic  prisms. 
Fuses  at  104°,  and  boils  at  271°.  It  is  very  soluble  in  water,  alcohol, 
and  ether.  Its  aqueous  solution  is  neutral  in  reaction,  and  intensely 
sweet.  With  FeCl3  its  solutions  assume  a  dark- violet  color,  which  is 
discharged  by  NH4OH.  Its  ammoniacal  solution  by  exposure  to 
air,  assumes  a  pink  color,  changing  to  brown  and,  on  evaporation, 
green  and  dark  blue.  Heated  with  phthalic  anhydride  at  195°  it 
yields  fluoresceme.  It  dissolves  in  fuming  H2S04,  forming  an 
orange-red  solution,  which  becomes  darker,  changes  to  greenish-black, 
then  to  pure  blue,  and  finally  to  purple  on  being  warmed. 

Resorcinol,  heated  with  sodium  nitrite  and  H20  to  about  150° 
yields  a  blue  pigment  known  as  lacmoid,  which  behaves  like  litmus 
with  acids  and  alkalies,  but  is  more  sensitive. 

Quinol  —  Hydroquinone  —  Paradioxy-benzene — C6H4  (OH)  2 (1  4)  is 
formed  by  fusing  paraiodo-phenol  with  KOH  at  180°,  by  dry  dis- 
tillation of  oxysalicylic  acid  or  of  quinic  acid,  and  by  the  action  of 
reducing  agents  on  quinone.  It  forms  colorless,  rhombic  prisms, 


350  TEXT-BOOK   OF   CHEMISTRY 

which  fuse  at  169°.  Readily  soluble  in  water,  alcohol,  or  ether.  Its 
aqueous  solution  is  turned  red-brown  by  NH4OH.  Oxidizing  agents 
convert  it  into  quinone. 

TRIATOMIC,  OR  TRIHYDRIC  PHENOLS. 

Phloroglucin — C0H3  ( OH )  3  (1  3  5)  — is  obtained  by  the  action  of 
potash  upon  phloretin,  quercitrin,  maclurin,  catechin,  kino,  etc.  It 
crystallizes  in  rhombic  prisms,  containing  2Aq;  is  very  sweet;  and 
very  soluble  in  water,  alcohol,  and  ether. 

Pyrogallol — Pyrogallic  acid — C6H3(OH)3(1  2  3) — is  formed  when 
gallic  acid  is  heated  to  200  °.  It  crystallizes  in  white  needles ;  neutral 
in  reaction;  very  soluble  in  water;  very  bitter;  fuses  at  132°;  boils 
at  210°;  poisonous^  Its  most  valuable  property  is  that  of  absorbing 
oxygen,  for  which  purpose  it  is  used  in  the  laboratory  in  the  form 
of  a  solution  of  potassium  pyrogallate. 

PHENOL  DYES. 

Aurin — C19H1403,  and  Rosolic  acid — C20H1803 — are  substances  existing  in 
the  dye  obtained  by  the  action  of  oxalic  acid  upon  phenol  in  presence  of  H2S04, 
known  as  corallin,  or  pceonin,  which  communicates  to  silk  or  wool  a  fine 
yellow-red  color. 

Aurin  crystallizes  in  fine,  red  needles  from  its  solution  in  HC1.  It  is  in- 
soluble in  H2O,  but  soluble  in  HC1,  alcohol,  and  glacial  acetic  acid.  It  forms 
a  colorless  compound  with  potassium  bisulphite. 

Phthaleins. — These  substances  are  produced  by  heating  the  phenols  with 
phthalic  anhydride,  C«H4(CO)2O,  water  being  at  the  same  time  eliminated. 

Their  constitution  is  that  of  a  benzene  nucleus,  two  of  whose  H  atoms  have 
been  replaced  by  two  acetone  groups  ( CO ) ,  whose  remaining  valences  attach 
them  to  two  phenol  groups  by  exchange  with  an  atom  of  hydrogen. 

Thus  phenol-phthalei'n,  the   simplest  of  the  group,   has   the  constitution, 

C.H4  (\       ~nflTT4!r  T!'     Phenol-phthalein  is  a  yellow,  crystal  powder,  insoluble 

\  \j\J — V^8H4  ( L/H ) . 

in  water,  but  soluble  in  alcohol.  Its  alcoholic  solution,  perfectly  colorless  if 
neutral,  assumes  a  brilliant  magenta-red  in  the  presence  of  an  alkali.  This 
property  renders  phenol-phthalei'n  very  valuable  as  an  indicator  of  reaction. 

Resorcinol-phthalem— Fluoresceme— C20H12O8— bears  the  same  relation  to 
resorcinol  that  phenol-phthalei'n  does  to  phenol,  and  is  obtained  from  resorcinol 
by  a  corresponding  method.  It  is  a  dark-brown  crystalline  powder,  whicli 
dissolves  in  ammonia  to  form  a  red  solution,  exhibiting  a  most  brilliant  green 
fluorescence.  A  tetra-bromo-derivative  of  fluorescme  is  used  as  a  dye  under  the 
name  eosin. 

QUINONES. 

The  quinones  are  benzene  derivatives  in  which  two  atoms  of 
hydrogen  are  replaced  by  two  oxygen  atoms.  The  attachment  of 
the  -0.0-  group  is  either  ortho-  or  para-,  never  meta-.  Ortho- 
quinones  of  the  polybenzenic  series,  such  as  ft  naphthoquinone  and 
anthroquinone,  are  well-known  compounds,  but  the  mono-benzenic 
ortho-quinones  are  only  known  in  their  derivatives. 


HC       CH 


C 


AROMATIC   ALCOHOLS  351 

The  monobenzenic  para-quinones  may  be  considered  either  as 
peroxides,  the  bonds  of  the  benzene  ring  remaining  intact  (Formula 

O  I),  or  they  may  be  considered  as 

ring-ketones    (Formula      II),      in 
which  the  two  CO  groups  form  a 
HC       CH          part  of  an  oxidized  hydroaromatic 

ring.     The  former  view  is  favored 
***•'  i      A-I      t>         ,1       .-i 

\/  by  the  facts  that  the  quinones  are 

strong  oxidizing  agents,  as  are  the 
[J  peroxides  in  general,  and  that  they 

(I).  (II.)  yield   monosubstituted   derivatives 

by  replacement  of  their  oxygen  by  univalents,  as  benzoquinone  forms 

//-^TT  %  /"iT"r\ 

p-dioxybenzene,     (HO)C^CH'CH^C(OH)     on    reduction,    and    p- 

dichlorobenzene,  C1C  ^CH'CH^CC1,  by  the  action  of  PC15.  On  the 
other  hand,  the  existence  of  the  C0=group  in  the  quinones  is  indi- 
cated by  the  fact  that  they  readily  form  oximes  with  hydroxylamine, 
a  reaction  characteristic  of  compounds  containing  C0=,  as  benzo- 

/CTT  •  PTTX 

quinone  forms  quinone  dioxime,  HO.NC  \CH  CH/C'N.OH;  an^  if»  by 
reason  of  its  oxidation  of  phenylhydrazine,  benzoquinone  forms  no 
phenylhydrazone  such  compounds  are  formed  by  the  naphtho- 
quinones. 

/O 
Quinone — Benzoquinone — C6H4:      | — is   formed   by   the   action 

of  oxidants  upon  a  variety  of  p-benzene  derivatives,  but  best  by 
limited  oxidation  of  quinic  acid.  It  crystallizes  in  golden-yellow 
prisms,  f.  p.  116°,  sublimes  at  ordinary  temperatures,  sparingly 
soluble  in  cold  water,  readily  soluble  in  hot  water,  alcohol  and  ether. 
It  has  a  peculiar,  pungent  odor,  stimulates  the  lachrymal  secretion, 
and  irritates  the  skin.  Reducing  agents  convert  it  into  quinol. 

AROMATIC  ALCOHOLS. 

The  alcohols  corresponding  to  this  series  of  hydrocarbons  are 
isomeric  with  the  phenols.  They  contain  the  characterizing  group  of 
the  primary  alcohols,  CH2OH ;  once  if  the  alcohol  be  monoatomic, 
twice  if  diatomic,  etc.,  and  they  yield  on  oxidation,  first  an  aldehyde 
and  then  an  acid.  Thus:  C6H5.CH2OH=benzylic  alcohol;  C6H5.- 
CHO=benzoic  aldehyde;  C6H5.COOH=benzoic  acid. 

The  monohydric  aromatic  alcohols  are  produced  by  reactions  sim- 
ilar to  those  by  which  the  corresponding  aliphatic  compounds  are 
produced  (p.  212)  : 

(1)  By  reduction  of  the  corresponding  aldehydes: 

C6H5.CHO+H2=C6H5.CH2OH 


352  TEXT-BOOK   OF   CHEMISTRY 

(2)  By  saponification  of  alkyl  benzenes  having  a  halogen  atom 
in  a  lateral  chain: 

C6H5.CH2C1+KOH=KC1+C6H5.CH2OH 

(3)  By  the  action  of  nitrous  acid  on  the  primary  amides  having 
the  amido  group  in  a  lateral  chain: 

C0H5.CH2.NH2+NH02=:H20+N2+C6H5.CH2OH 

(4)  By  reduction  of  the  unsaturated  alcohols  such  as  cinnamic 
alcohol  : 

C6H5.CH:CH.CH2OH+H2=C6H5.CH2.CH2.CH2OH 

(5)  By  the  action  of  trioxymethylene  upon  phenyl  magnesium 
halides  : 

C6H5.Mg.Br+H.CHO=C6H5.CH2O.MgBr  and 

C6H5CH2O.MgBr+H20=C6H5CH2OH+HO.Mg.Br 

They  are  capable  of  yielding  isomeric  products  of  further  sub- 
stitution, ortho,  para,  or  meta. 

Benzylic  Alcohol  —  Benzoic  Alcohol  —  Benzyl  Hydrate  —  C6H5.- 
CILOH  —  does  not  exist  in  nature,  and  is  of  interest  chiefly  as  cor- 
responding to  two  important  compounds,  benzoic  acid  and  benzoic 
aldehyde  (oil  of  bitter  almonds).  It  is  obtained  by  the  action  of 
potassium  hydroxide  upon  oil  of  bitter  almonds,  or  by  slowly  adding 
sodium  amalgam  to  a  boiling  solution  of  benzoic  acid. 

It  is  a  colorless  liquid  ;  boils  at  206.5  °  ;  has  an  aromatic  odor  ;  is 
insoluble  in  water,  soluble  in  all  proportions  in  alcohol,  ether,  and 
carbon  bisulphide.  By  oxidation  it  yields,  first,  benzoic  aldehyde, 
C6H5CHO  ;  and  afterward,  benzoic  acid,  C0H5.COOH.  By  the  same 
means  it  may  be  made  to  yield  products  similar  to  those  obtained 
from  the  alcohols  of  the  saturated  hydrocarbons. 

Secondary  and  tertiary  aromatic  alcohols  are  also  known,  such  as 
phenyl-methyl  carbinol,  C6H5.CHOH.CH3  and  phenyl-dimethyl  carbinol, 
CflH6.COH  (  CH3  )  2-  The  secondary  alcohols  yield  ketones  on  oxidation  (p.  354). 

Di-  and  tri-hydric  alcohols,  such  as  the  xylylene  glycols,  CaH4  (  CH2OH  )  2, 
and  mesitylene  glycerol,  CaH3.  (  CH2OH  )  3  (1^6),  are  also  known,  as  well  as 
alcohols  with  unsaturated  lateral  chains,  such  as  cinnamic  alcohols,  C6HS.CH:- 
CH.CHjOH,  which  occurs  as  its  cinnamic  ester  in  storax.  It  oxidizes  to  cinnamic 
aldehyde  and  cinnamic  acid. 

ALPHENOLS,  OR  OXYPHENYL  ALCOHOLS. 

These  substances  are  intermediate  in  function  between  the  alcohols  and 
the  phenols,  and  contain  both  substituted  groups  OH  and  CHaOH. 


OTT 
Saligenin—  o-Oxybenzylic  Alcohol  —  C.HQg2      —is  obtained  from  salicin 


in  large,  tabular  crystals;  quite  soluble  in  alcohol,  water,  and  ether.  Oxidizing 
agents  convert  it  into  salicylic  aldehyde,  which  by  further  oxidation  yields 
salicylic  acid.  It  is  also  formed  by  the  action  of  nascent  hydrogen  on  salicylic 
aldehyde. 


ALDEHYDES  353 

ALDEHYDES. 

The  aromatic  aldehydes  are  the  first  products  of  oxidation  of 
the  aromatic  alcohols.  Monaldehydes  containing  one  CHO  group 
and  dialdehydes  containing  two  such  groups  are  known. 

The  monaldehydes  are  formed:  (1)  By  oxidation  of  the  alcohols; 

(2)  By  decomposition  of  the  alcohol  bichlorides  by  water: 

C6H5.CHC12+H20=C6H5.CHO+2HC1. 

(3)  By  oxidation  of  the  alcohol  monochlorides  by  lead  nitrate: 

C6H5.CH2C1+0=C6H5.CHO+HC1 

(4)  By  distilling  a  mixture  of  the  Ca  salt  of  the  acid  and  calcium 
formate : 

(C6H5.COO)  2Ca+  (H.COO)  2Ca=2C6H5.CHO+2CaC03 

(5)  By  prolonged  boiling  of  phenyl  magnesium  halides  with  or- 
thoformic  esters,  and  hydrolysis  of  the  product: 

C6H5.MgBr.+CH;(O.C2H5)3=C6H5.CH:(O.C2H5)2+C2H5O.Mg.Br. 
andC6H5.CH:(O.C2H5)2+H20=C6H5.CHO+2C2H5.OH 

(6)  By  the  action  of  chromyl  chloride,  Cr02Cl2,  upon  the  hydro- 
carbons, and  decomposition  of  the  addition  compound  by  water. 

Benzoic  Aldehyde — Benzoyl  hydride — C6H5.CHO — is  the  main 
constituent  of  oil  of  bitter  almonds,  although  it  does  not  exist  in 
the  almond.  It  is  formed,  along  with  hydrocyanic  acid  and  glucose, 
by  the  action  of  water  upon  amygdalin.  It  is  also  formed  by  the 
general  methods  given  above ;  by  the  dehydration  of  benzylic  alcohol ; 
by  the  dry  distillation  of  a  mixture  in  molecular  proportions  of  cal- 
cium benzoate  and  formate;  by  the  action  of  nascent  hydrogen  upon 
benzoyl  cyanide,  etc.  It  is  obtained  from  bitter  almonds.  The  crude 
oil  contains,  besides  benzoic  aldehyde,  hydrocyanic  and  benzoic  acids 
and  benzoyl  cyanide. 

It  is  a  colorless  oil,  having  an  acrid  taste  and  the  odor  of  bitter 
almonds;  sp.  gr.  1.050;  boils  at  179.4°;  soluble  in  30  parts  of  water, 
and  in  all  proportions  in  alcohol  and  ether.  Oxidizing  agents  con- 
vert it  into  benzoic  acid,  a  change  which  occurs  by  mere  exposure 
to  air.  Nascent  hydrogen  converts  it  into  benzylic  alcohol.  With 
Cl  and  Br  it  forms  benzoyl  chloride  or  bromide :  H2S04  dissolves  it 
when  heated,  forming  a  purple-red  color,  which  turns  black  if  more 
strongly  heated.  It  forms  a  series  of  products  of  substitution,  haloid, 
nitro,  amido,  etc. 

When  perfectly  pure,  benzoic  aldehyde  exerts  no  deleterious  action 
when  taken  internally ;  owing,  however,  to  the  difficulty  of  com- 
pletely removing  the  hydrocyanic  acid,  the  substances  usually  sold  as 
oil  of  bitter  almonds,  ratafia,  and  almond  flavor,  are  almost  always 
poisonous,  if  taken  in  sufficient  quantity.  They  may  contain  as 


354  TEXT-BOOK   OF   CHEMISTRY 

much  as  10-15  per  cent,  of  hydrocyanic  acid,  although  said  to  be 
"purified."  The  presence  of  the  poisonous  substances  may  be  de- 
tected by  the  tests  given  on  page  304. 

Salicylic  Aldehyde — Salicyl  hydride — Salicylal — Salicylous  acid 
—o-Oxybenzaldehyde — C6H4(OH)  (CHO)(2) — exists  in  the  flowers  of 
Spircea  ulmaria,  and  is  the  principal  ingredient  of  the  essential  oil 
of  that  plant.  It  is  best  obtained  by  oxidizing  salicin. 

It  is  a  colorless  oil ;  turns  red  on  exposure  to  air ;  has  an  agree- 
able, aromatic  odor,  and  a  sharp,  burning  taste;  sp.  gr.  1.173  at 
13.5;  boils  at  196.5°;  soluble  in  water,  more  so  in  alcohol  and  in 
ether. 

It  is,  as  we  should  suspect  from  its  origin,  a  substance  of  mixed 
function,  possessing  the  characteristic  properties  of  aldehyde  and 
phenol,  an  oxymonaldehyde,  or  phenol  aldehyde.  Compounds  of  this 
class  are  formed  by  the  action  of  chloroform  upon  the  phenols  in  the 
presence  of  a  caustic  alkali,  when  the  CHO  enters  the  ortho-  or  para- 
position  with  reference  to  the  phenolic  hydroxyl.  Thus  phenol  yields 
ortho-  or  para-salicylic  aldehyde: 

C6H5OH+CHCl3+4KOH=3KCl+3H20+C6H4.(OK)(i)  (CHO)(2)  (r(4) 

It  produces  a  great  number  of  derivatives,  some  of  which  are  salts 
or  esters,  such  as  p-methoxybenzaldehyde,  or  anisic  aldehyde, 
C6H4(CHO)(OCH3)  w,  a  product  of  oxidation  of  anethol. 

Vanillin — Methylprotocatechuic  Aldehyde  —  m-Methoxy-p-oxybenzalde- 
hyde— C6H3.CHO.(O.CH3)  (3)(OH)  (4)— a  methylated  dioxybenzaldehyde,  is  the 
odoriferous  principle  of  vanilla.  It  is  produced  artificially  by  oxidation  of 
coniferin,  C16H2208,  a  glucoside  occurring  in  coniferous  plants.  It  crystallizes 
in  needles,  fuses  at  80°,  is  sparingly  soluble  in  water,  readily  soluble  in  alcohol 
or  ether.  It  has  a  pungent  taste  and  a  persistent  odor  of  vanilla.  On  ex- 
posure to  air  it  becomes  partly  oxidized  to  vanillic  acid,  C8H804. 

KETONES. 

The  aromatic  ketones  are  produced  by  the  oxidation  of  the  sec- 
ondary aromatic  alcohols : 

2C6H5.CHOH.CH3+02=2H20+2C6H5.CO.CH3 

Or  by  the  action  of  caustic  potash  upon  the  aromatic  ft  ketone- 
carboxylic  acids: 

C6H5.CO.CH2.COOH+2KOH=C6H5.CO.CH3-j-H20+K2C03 

Monoketones,  diketones  and  triketones,  containing  one,  two  and 
three  lateral  chains  with  CO  groups,  are  known.  The  monoketones, 
also  called  phenones,  consist  of  a  closed  chain  hydrocarbon  group 
united  to  an  open  chain  one  by  the  group  (CO)".  They  may  also  be 
considered  as  benzene,  into  which  fatty  acid  radicals  have  been  sub- 
stituted for  hydrogen. 

The  phenones  containing  two  aromatic  nuclei,  as  benzophenone : 
C6H5.CO.C0H5,  belong  to  the  diphenyl  derivatives. 


AROMATIC    CARBOXYLIC   ACIDS  355 

The  phenones  are  acted  upon  by  the  alkyl  magnesium  halides  in 
the  same  manner  as  are  those  of  the  aliphatic  series  (p.  226).  Thus 
benzophenone  and  phenyl  magnesium  bromide  produce  triphenyl 
carbinol : 

(C6H5)2:CO+C6H5.Mg.Br.=  (C6H5)2:C(C6H5).OMg.Br,  and 
(C6H5)2:C(C6H5)O.MgBr+H20=(C6H5)3lCOH+HO.Mg.Br 

Phenyl-methyl  Ketone — Acetyl  benzene — Acetophenone — Hyp- 
none — C6H5.CO.CH3 — is  obtained  by  distilling  a  mixture  of  calcium 
benzoate  and  acetate ;  by  the  action  of  zinc-methyl  upon  benzoyl 
chloride ;  or  by  the  action  of  acetyl  chloride  or  bromide  upon  benzene 
in  the  presence  of  aluminium  chloride.  It  forms  large  crystalline 
plates,  fusible  at  20°.  It  has  been  used  as  a  hypnotic. 

Acetophenone  Oxime — C6H5.C:(N.OH).CH3 — is  isomeric  with 
acetanilide,  C6H5NH(CO.CH3),  and  is  converted  into  that  substance 
by  the  action  of  concentrated  H2S04. 

AROMATIC  CARBOXYLIC  ACIDS. 

All  six  of  the  hydrogen  atoms  of  benzene  are  replaceable  by 
carboxyl  groups,  with  formation  of  monocarboxylic  acids,  dicarboxylic 
acids,  etc.  There  are  also  three  series,  o-,  m-,  and  p-,  of  the  bi-, 
tri-,  and  tetracarboxylic  acids,  and  of  the  monocarboxylic  acids  above 
the  first.  These  acids  may  be  obtained  by  oxidation  of  the  cor- 
responding alcohols,  or  aldehydes,  where  these  are  known.  Like  the 
aliphatic  acids,  they  may  be  considered  as  being  derived  from  the 
hydrocarbons  by  substitution  of  hydroxyl  and  oxygen  for  hydrogen 
in  a  lateral  chain. 

MONOCARBOXYLIC    AROMATIC    ACIDS— BENZOIC    SERIES. 

These  acids  are  formed  by  many  methods,  among  which  the  most 
important  are :  ( 1 )  By  oxidation  of  the  lateral  chain  in  hydrocarbons 
homologous  with  benzene.  Thus  toluene  yields  benzoic  acid: 

2C6H5.CH3+302=2C6H5.COOH+2H20 

(2)  By  oxidation  of  the  corresponding  alcohols  and  aldehydes. 

(3)  By  the  action  of  sodium  and  carbon  dioxide  upon  the  mono- 
bromobenzenes :          , 

C6H5Br+C02+2Na=NaBr+C6H5.COONa 

(4)  By  decomposition  of  the  aromatic  acid  nitriles  by  acids  or 
alkalies : 

C6H5.CN+KOH+H20=C6H5.COOK+NH3 

(5)  By  fusion  of  the  aromatic  sulphonic  acids  with  sodium  form- 
ate: 

C6H5.S03Na+H.COONa=C6H5.COONa+NaHS03 


356  TEXT-BOOK   OF    CHEMISTRY 

The  acids  of  this  scries  form  many  derivatives.  In  some  of  these 
the  carboxyl  is  modified,  leaving  either  the  radical  benzoyl,  C6H5.CO, 
as  in  benzamide,  C6H5.CO.NH2,  or  the  trivalent  group  benzenyl, 
C6H5.C,  as  in  benzenyl-amidine,  C6H5.C^^.  In  others  the  substi- 
tution occurs  in  the  benzene  ring,  as  in  the  oxy-,  halogen-,  and 
nitro-benzoic  acids,  etc.,  e.  g.  anthranilic  or  o-amido-benzoic  acid 
C6H4.COOH(1)(NH2)(2). 

Benzoic  Acid — C6H5.COOH — exists  in  benzoin,  tolu  balsam,  cas- 
toreum,  and  in  several  resins.  It  is  obtained  by  the  general  methods 
given  above;  also  from  benzoin,  and  from  the  urine  of  herbivorous 
animals.  The  urine  contains  hippuric  acid,  which,  on  decomposition, 
yields  benzoic  acid.  Conversely,  when  benzoic  acid  is  taken  into  the 
body  in  moderate  doses  it  is  eliminated  as  hippuric  acid. 

Benzoic  acid  crystallizes  in  white,  transparent  plates;  the  solid 
acid  is  odorless,  but  its  vapor  has  a  peculiar  odor  and  produces  a 
tendency  to  sneeze;  it  is  sparingly  soluble  in  cold  water,  readily 
soluble  in  hot  water,  in  alcohol  and  in  ether;  fuses  at  120°,  boils 
at  250°,  and  sublimes  at  temperatures  below  its  boiling  point.  Ben- 
zoic  acid  is  not  attacked  by  HN03.  Heated  with  lime,  it  yields  ben- 
zene and  calcium  carbonate: 

C6H5.COOH+CaH202=,C6H6+CaC03+H20 

a  reaction  corresponding  to  the  formation  of  methane  from  sodium 
acetate.  The  benzoates  are  all  soluble,  the  least  soluble  being  the 
ferric  salt. 

Homologues  of  Benzoic  Acid. — These  are  of  two  kinds:  (1)  Those  in 
which  the  carboxyl  and  hydrocarbon  groups  replace  different  hydrogen  atoms, 
the  alkyl-benzoic  acids,  as  cumic  acid,  or  p-isopropyl  benzoic  acid, 
C6H4. ( C3HT ) (i)  ( COOH )  w.  (2)  Those  in  which  the  carboxyl  is  separated  from 
the  benzene  ring  by  a  hydrocarbon  group,  the  phenyl  fatty  acids,  as  phenyl- 
acetic  acid,  C^Hj.CH^COOH.  In  the  terms  above  the  first  of  this  series  there 
are  place  isomeres  according  to  the  distance  from  the  ring  in  which  the  carboxyl 

/POOTT 

is  introduced.  Thus  a  phenyl-propionic  acid,  C«HB.CH  \ng  and  $  phenyl- 
propionic  acid,  CeH5.CH2.CH2.COOH. 


POLYCARBOXYLIC  AROMATIC  ACIDS. 

The  di-,  tri-,  tetra-,  penta-,  and  hexa-carboxylic  aromatic  acids  are  derived 
from  benzene  by  substitution  of  from  two  to  six  carboxyls  for  hydrogen  atoms. 
Of  the  superior  homologues  there  exist  a  number  of  isomeres,  increasing  with 
the  number  of  carbon  atoms,  according  as  the  carboxyls  are  attached  to  the 
benzene  ring,  as  in  the  phthalic  acids,  or  are  contained  in  lateral  chains,  as  in 
phenyl-malonic  acid,  C6HVCH  ( COOH )  2,  and  varying  further  by  differences  in 
orientation  either  in  the  benzene  or  the  lateral  chains. 

Phthalic  Acids— C8H4  ( COOH )  2 — Ortho-,  meta-,  and  para-phthalic  acids 
are  produced  by  oxidation  of  the  corresponding  bisubstituted  benzene  derivatives, 
and  serve  by  their  formation  to  determine  whether  a  given  compound  is  o-, 
m-,  or  p-. 


PHENOL    CARBOXYLIC   ACIDS   AND   THEIR   ESTERS  357 

Phthalic  Acid — Benzene-o-dicarboxylic  acid — CaH4  ( COOH )  2  a,  2> — is  ob- 
tained :  ( 1 )  industrially  by  oxidation  of  naphthalene  or  tetra-chloronaphthalene, 
for  usa  in  the  manufacture  of  the  phthalei'n  dyes ;  ( 2 )  by  oxidation  of  o-xylene, 
o-toluic  acid,  etc.;  (3)  by  direct  union  of  carbon  monoxide  with  salicylic  acid: 

C6H4.OH.COOH-f-CO=:C6H4  ( COOH )  2 
or  with  resorcinol: 

C6H4  ( OH )  2-f 2CO=C6H4  ( COOH )  2 

Phthalic  acid  crystallizes  in  prisms,  sparingly  soluble  in  cold  water,  readily 
soluble  in  hot  water,  alcohol,  and  ether,  fuses  at  213°.  Heated  with  excess  of 
Ca(OH)2,  it  is  decomposed  into  benzene  and  CO2;  but  when  its  Ca  salt  is  heated 
to  350°  with  one  molecule  of  Ca(OH)2  only  one  CO2  is  expelled,  leaving 
calcium  benzoate.  Nascent  hydrogen  converts  it  into  hydrophthalic  acids. 
It  is  the  only  phthalic  acid  which  yields  an  anhydride. 

Isophthalic  Acid — Benzene-m-dicarboxylic  acid — C6H4  ( COOH )  2  a,  s>  — is 
formed  by  oxidation  of  m-xylene,  m-toluic  acid,  and  other  m-benzene  bisubsti- 
tuted  derivatives.  It  crystallizes  in  fine  needles,  sparingly  soluble  in  water, 
soluble  in  alcohol,  fuses  and  sublimes  above  300°. 

Terephthalic  Acid — Benzene-p-dicarboxylic  acid — C6H4  ( COOH )  2  <i,  *>  — is 
formed  by  oxidation  of  p-xylene,  p-toluic  acid,  and  other  p-benzene  bisubstituted 
derivatives.  It  is  insoluble  in  water,  alcohol,  and  ether,  and  sublimes  without 
melting. 

PHENOL  CARBOXYLIC  ACIDS  AND  THEIR  ESTERS. 

These  compounds  have  both  hydroxyl  and  carboxyl  attached  to 
the  benzene  ring.  They  have  the  functions  of  phenol  and  of  acid. 
They  are  formed  (1)  by  fusing  the  sulphobenzoic  acids  with  alkalies: 

C6H4(COOH)S03H+KOH=S03HK+C6H4(COOH)(OH) 
also  similarly  from  the  haloid  acids: 

C6H5.Br.COOH+KOH=C6H4.OH.COOH+KBr 

(2)  By  fusion  of  the  homologues  of  phenol  with  caustic  potash, 
the  methyl  of  the  hydrocarbon  lateral  chain  is  oxidized  to  carboxyl. 

(3)  By  oxidation  of  the  phenol-aldehydes  by  fusion  with  caustic 
alkalies. 

(4)  By  saponification  of  their  esters,  produced  by  oxidizing  the 
sulphuric  or  phosphoric  esters  of  the  homologues  of  phenol. 

(5)  By  heating  the  phenols  with  carbon  tetrachloride  and  caustic 
potash : 

C6H5.OH+CC14+4KOH=C6H4.OH.COOH+2H20+4KC1 

(6)  By  the  action  of  carbon  dioxide  upon  the  sodium  phenates: 

2C6H5.O.Na+C02=C6H4.O.Na.COONa+C6H5.OH 
Di-,  tri-,  and  tetra-carboxylic  oxyacids  are  known.    But  the  best 
known  of  the  oxyacids  are  monocarboxylic,  and  monoxy-,  dioxy-,  and 
trioxy-,  corresponding  to  the  phenols  of  like  hydroxyl  content. 

MONOXY-MONOCARBOXYLIC   ACIDS. 

Oxybenzoic  Acids— C6H4.OH.COOH.— Of  the  three  isomeric 
acids  the  meta-,  f.  p.  200°,  and  the  para-,  f.  p.  210°,  acids  are  ob- 


358  TEXT-BOOK   OF   CHEMISTRY 

tained  by  the  action  of  KOH  on  the  corresponding  bromobenzoic 
acids. 

Salicylic  Acid— o-Oxybenzoic  Acid — f.  p.  155°  occurs  free, 
accompanied  by  salicylic  aldehyde,  in  Spiraea  ulmaria  and,  as  its 
methylic  ester,  in  oil  of  wintergreen.  It  is  also  formed  by  decom- 
position of  salicin,  coumarin  or  indigo.  It  is  produced  synthetically 
by  the  above  reactions  and,  industrially,  by  heating  sodium  phenate 
in  a  current  of  carbon  dioxide.  The  reaction  is  not 

C6H5.ONa+C02=C6H4.OH.COONa,  but 
2C6H5.ONa+C02=C6H5.OH+C6H4.ONa.COONa 

Salicylic  acid  crystallizes  in  prisms  or  needles,  sparingly  soluble 
in  cold  water,  readily  soluble  in  hot  water,  alcohol  and  ether,  sweet 
and  acid  in  taste.  When  heated,  it  distils  in  part  unchanged,  while 
a  part  loses  oxygen  and  yields  salol  and  xanthone,  C13H1002 ;  or  salol, 
carbon  dioxide  and  water.  With  Cl  and  Br  it  forms  products  of  sub- 
stitution. With  fuming  HN03  it  forms  a  nitro-acid  and  finally, 
picric  acid.  With  ferric  chloride  it  gives  a  fine  violet  color.  Nascent 
hydrogen  causes  rupture  of  the  ring,  with  formation  of  pimelic  acid 
as  a  final  product.  Salicylic  acid  and  its  salts  and  esters  are  used 
as  antiseptics  and  as  antirheumatics. 

Phenyl  Salicylate— Salol— C6H4.OH.COO(C6H5)—  is  formed  by 
heating  salicylic  acid  to  220°: 

2C6H4.OH.COOH=C6H4.OH.COO  ( C6H5 )  +C02+H20 

also  by  the  action  of  POC13  on  a  mixture  of  salicylic  acid  and 
phenol.  It  is  a  white,  crystalline  powder,  faintly  aromatic  in  taste 
and  odor,  almost  insoluble  in  water,  soluble  in  alcohol,  ether  and 
benzene,  fuses  at  43°.  It  is  not  decomposed  by  weak  acids,  but  is 
saponified  by  alkalies  to  form  salicylic  acid  and  phenol;  hence  it 
passes  unchanged  through  the  stomach  to  be  decomposed  in  the 
intestine : 

C6H4.OH.COO(CCH5)+H20=C6H4.OH.COOH+C6H5.OH 

Acetol  Salicylate  — Salacetol  —  C6H4.OH.COO(CH2.CO.CH3)- 
the  ester  of  the  keto-alcohol,  acetol,  is  formed  by  the  action  of  mono- 
chloracetone  on  sodium  salicylate.  It  crystallizes  in  plates,  spar- 
ingly soluble  in  water,  readily  soluble  in  alcohol,  fusible  at  71°. 
It  is  saponified  by  alkalies  with  formation  of  acetol  and  salicylic  acid, 
and  is  hence  substituted  for  salol  as  a  medicine  when  the  formation 
of  phenol  is  undesirable.  Like  acetol  and  its  other  esters,  it  reduces 
Fehling's  solution. 

DI-  AND  TRIOXYMONOCARBOXYLIC  ACIDS. 

Dioxycarboxylic    Acids. — The    six    isomeres    corresponding    to    the    three 
diphenols  are  known,  as  well  as  numerous  alkyl  derivatives,  such  as  vanillic, 


PHENOL    CARBOXYLIC   ACIDS   AND   THEIR   ESTERS 


359 


isovanillic*  and    veratric    acids,    which    are    derived    from    protocatechuic    acid. 
The  relations  of  these  acids  are  shown  by  the  following  formulae: 


PYROCATECHOL. 
OH 


O=  3.4-Dioxybenzoic. 

=  Protocatechuic. 
/3=  2.3-Dioxybenzoic, 


0(CH8) 


COOH 
Vanilllc  acid. 


RESORCINOL. 
OH 


a-Resorcylic, 

=  3. 5-Dioxy  benzole, 

/3—  Resorcylic, 

=  2.4-Dioxybenzoic. 

7  Resorcylic, 

=  2.6-Dioxybenzoic. 


0(CH3) 


OH 


COOH 

Isovanillic  acid. 


QUINOL. 
OH 


OH 

2. 5-Dioxy  benzoic, 

=  Gentisinic, 

=  Hydroquinone-carboxylic. 


COOH 

Veratric  acid. 


Protocatechuic  Acid — 3.4-Dioxybenzoic  Acid— C6H3  ( COOH )  a)  ( OH )  2  &*) 
— exists  in  the  fruit  of  the  star-anise,  and  is  produced  from  many  resins  by 
fusion  with  KOH.  It  is  formed  by  fusion  of  dibromobenzoic  acid,  and  other 
similar  derivatives,  with  KOH. 

The  superior  homologues  of  dioxycarboxylic  acids  are  either  dioxytoluic 
acids,  etc.,  such  as  orsellinic  acid,  or  dioxy-phenyl  fatty  acids,  such  as  homo- 
gentisinic  acid: 


COOH 


CHo.COOH 


OH 


CH2.COOH 


HO 


CH3 

2.6-Dioxyparatoluic. 
=  Orsellinic. 


2.5-Dioxyphenyl-acetic. 
=  Homogentisinic. 


OH 

3.4-Dioxyphenyl-acetic. 
=Homoprotocatechuic. 


CH2CHOH.COOH 


3.4-Dioxypbenyl-lactic. 
=  Uroleucic    (?) 


Homogentisinic  acid,  or  glycosuric  acid,  exists  in  the  urine  in  "  alkap- 
tonuria,"  probably  accompanied  by  homoprotocatechuic  and  uroleucic  acids, 
as  well  as  by  the  monoxy-monocarboxylic  acids  mentioned  above. 

Trioxycarboxylic  Acids. — Three  of  the  six  possible  acids  are  known,  two 
derived  from  pyrogallol,  one  from  phloroglucin. 

Gallic  Acid — C6H2(COOH)(i)(OH)3(3, 4, 5) — exists  in  nature  in  certain  leaves, 
seeds  and  fruits.  It  is  best  obtained  from  nut-galls,  which  contain  its  glucoside, 
gallo-tannic  acid.  It  is  formed  when  bromo-protocatechuic  acid  is  fused  with, 


360  TEXT-BOOK   OF    CHEMISTRY 

caustic  potash.  It  crystallizes  in  long,  silky  needles  with  lAq,  odorless,  acidu- 
lous in  taste,  sparingly  soluble  in  cold  water,  very  soluble  in  hot  water  and 
in  alcohol.  Its  solutions  are  acid.  When  heated  to  210-215°  it  yields  CO2  and 
pyro-gallol.  Its  solutions  reduce  the  salts  of  silver  and  of  gold;  they  do  not 
precipitate  gelatin  nor  the  salts  of  the  alkaloids,  as  does  tannin;  and  they 
give  a  blue-black  precipitate  with  FeCl3. 

Tannins — Tannic  Acid — are  substances  of  vegetable  origin,  principally  de- 
rived from  leaves,  barks  and  seeds.  They  are  amorphous,  soluble  in  water, 
astringent,  capable  of  precipitating  albumin,  of  forming  imputrescible  com- 
pounds with  the  gelatinoids  (leather),  and  give  green  or  blue  colors  with  the 
ferric  salts. 

Pure  tannic  acid  has  been  obtained  by  removal  of  water  from  gallic  acid: 
2C7H6O5=C14H10O9-f-Hs!O;  it  is,  therefore,  digallic  acid.  It  exists  in  gall-nuts, 
excrescences  produced  upon  oak  trees  by  the  punctures  of  certain  insects  (gallo- 
tannic  acid ) .  It  is  colorless,  amorphous,  odorless,  very  soluble  in  water,  less  so 
in  alcohol,  almost  insoluble  in  ether.  It  forms  a  dark-blue  liquid  (ink)  with 
solutions  of  ferric  salts  or,  after  exposure  to  air,  with  ferrous  salts. 

Caffetannic  Acid,  C30H1BO,6,  exists  in  saline  combination  in  coffee  and 
Paraguay  tea.  It  colors  the  ferric  salts  green,  precipitates  the  salts  of  quinine 
and  cinchonine,  but  not  tartar  emetic  or  gelatin,  as  tannic  acid  does.  It  yields 
caffeic  acid,  or  3-4  dioxycinnamic  acid,  C9H8O4,  on  decomposition.  Cachou- 
tannic  acid  obtained  from  catechu,  is  soluble  in  water,  alcohol  and  ether.  It  pre- 
cipitates gelatin,  but  not  tartar  emetic,  and  colors  ferric  salts  grayish-green. 
Morintannic  acid,  or  maclurine,  C13Hi0O6,  is  a  yellow,  crystalline  substance,  ob- 
tained from  fustic.  It  is  more  soluble  in  alcohol  than  in  water.  Its  solutions 
precipitate  greenish-black  with  ferric  salts,  yellow  with  lead  acetate,  brown 
with  tartar  emetic  and  yellowish-brown  with  cupric  sulphate.  Quercitannic 
acid,  ClttHi6O,0,  is  the  tannin  of  oak  bark.  It  is  a  red  powder,  sparingly  soluble 
in  water,  which  forms  a  violet-red  precipitate  with  ferric  salts.  Quinotannic 
acid  exists  in  cinchona  barks,  in  combination  with  the  alkaloids.  It  is  light 
yellow,  soluble  in  water,  alcohol  and  ether,  astringent,  but  not  bitter  in  taste. 
It  is  colored  green  by  ferric  salts.  Dilute  H2S04  decomposes  it  with  formation 
of  quina  red,  an  amorphous  substance,  which  yields  protocatechuic  and  acetic 
acids  on  further  decomposition. 

PHENYLIC  ETHERS— GLUCOSIDES. 

The  oxides  of  the  aromatic  series,  corresponding  to  the  aliphatic  ethers, 
and  containing  two  cyclic  hydrocarbon  groups  united  by  an  oxygen  atom, 
properly  belong  among  the  dibenzenic  compounds  but  are  more  conveniently 
considered  here. 

Phenyl  Ether — Diphenyl  Oxide— (CaH5)2O— is  formed  by  heating  phenol 
with  aluminium  chloride,  or  with  zinc  chloride: 

2C8H8.OH=C6H5.O.C6H5+HJ0  f 

and  by  other  more  circuitous  methods.  It  crystallizes  in  long  needles, 
having  the  odor  of  geranium,  soluble  in  alcohol  and  in  ether.  Corresponding  to 
it  are  a  number  of  derivatives,  formed  by  substitution  of  various  univalents  for 
the  remaining  phenol  hydrogen. 

The  mixed  oxides,  containing  a  phenyl  and  an  alkyl  group,  are  the  phenyl 
ethers  or  phenol  esters,  derived  from  phenol.  They  are  formed  by  heating 
metallic  phenates  with  alkyl  halides: 

CflH5.O.K+CH8I=C6H5.O.CH,-fKI 

as  the  aliphatic  ethers  are  produced  from  metallic  alcoholates  and  alkyl  halides. 
Methyl-phenyl    Ether— Anisol— C6H5.O.CH8— is    a    colorless,    thin    liquid, 


GLUCOSIDES  361 

boils  at  152°   without  decomposition.     Sulphuric  acid  dissolves  it,  with  forma- 
tion of  irfethyl-phenol  sulphonic  acid. 

Ethyl-phenyl  Ether — Phenetol — C6H5.O.C2H5 — is  a  colorless  liquid,  having 
an  aromatic  odor.  It  boils  at  172°. 

GLUCOSIDES. 

The  name  "glucoside"  was  first  applied  to  certain  natural  prod- 
ucts, some  of  which  are  the  active  constituents  of  medicinal  plants, 
which,  on  decomposition  by  dilute  mineral  acids,  yield  glucose  and 
some  other  substance.  Subsequently,  it  was  found  that  the  sugars 
derived  from  some  of  these  substance",  differ  from  glucose;  some  are 
pentoses,  others  hexoses;  some  monosaccharides,  others  disaccharides ; 
some  aldoses,  others  ketoses.  On  the  other  hand,  the  second  product 
of  decomposition  has  been  of  the  most  varied  character,  phenols, 
alphenols,  alcohols,  oxyphenols,  monobenzenic  or  dibenzenic,  but,  in 
all  those  natural  glucosides  which  have  been  investigated,  always  a 
cyclic  compound,  containing  a  phenolic  or  an  alcoholic  group.  The 
glucosides  have  usually  been  regarded  as  esters  of  glucose,  etc.,  since 
the  alcoholic  character  of  the  sugars  has  been  recognized,  but,  as 
the  union  of  the  sugar  and  benzenic  components  is  through  an  oxygen 
atom,  and  not  by  replacement  of  the  hydrogen  of  a  carboxyl,  they 
are  more  properly  regarded  as  ethers,  formed  by  union  of  an  aldose 
or  ketose  remainder  with  one  of  a  phenolic  or  alcoholic  benzenic 
compound,  with  elimination  of  H20.  The  constitution  of  the  gluco- 
sides cannot,  however,  be  considered  as  established,  as  no  natural 
glucoside  has  been  obtained  synthetically,  although  the  products  of 
decomposition  of  some  are  comparatively  simple  compounds.  It 
is  to  be  supposed  that  the  union  takes  place  through  the  aldehyde 
group,  as  the  glucosides  do  not  reduce  Fehling's  solution  and  do 
not  form  osazones.  They  probably  contain  some  such  grouping  as: 

/ON 

CH2OH.(CHOH)3.CH CH.O.B,  in  which  B  represents  the  ben- 
zenic component. 

The  glucosides  are  decomposed  (hydrolyzed)  by  heating  with 
dilute  acids,  or,  at  very  slightly  elevated  temperatures,  by  certain 
enzymes,  such  as  emulsin,  which  exists  in  almonds,  myrosin,  in  mus- 
tard seeds,  the  invertin  of  malt,  and  salivary  and  intestinal  enzymes. 
They  are  very  slowly  hydrolyzed  by  heating  with  water  under,  pres- 
sure, if  at  all ;  and  only  a  few  of  them  are  decomposed  by  alkalies. 

The  glucosides  yielding  pentoses  on  hydrolysis  are  more  properly 
designated  pentosides. 

Phenyl  Glucosides— Glucosyl  phenate— CgH^Os.O.CeHg— is  the 
simplest  of  the  glucosides,  and  is  an  artificial  product,  formed  by 
mixing  alcoholic  solutions  of  acetochlorhydrose  and  potassium 
phenate : 

CHO.  ( CH.C02.CH3)  4.CH2C1+C6H5.O.K+4H20=CHO.  ( CHOH)  4.- 
CH2.O.C6H5+KC1+4CH3.COOH 


362  TEXT-BOOK   OF   CHEMISTRY 

It  forms  soluble,  crystalline  needles,  fusible  at  172°,  and  is  de- 
composed by  emulsin  into  glucose  and  phenol. 

Among  the  more  important  of  the  natural  glucosides  are  the  fol- 
lowing: 

JEsculin — Ci5H180B — which  exists  in  the  rinds  of  horse-chestnuts.  It  forms 
colorless  crystals,  sparingly  soluble  in  water,  the  solutions  having  a  brilliant 
blue  fluorescence,  even  when  very  dilute.  It  forms  a  yellow  solution  with 
HNO3,  which  becomes  deep  blood-red  on  supersaturation  with  ammonia.  It  is 
decomposed  by  dilute  mineral  acids,  or  by  emulsin,  into  glucose  and  aesculetin, 

/CH:CH 
CoH.Oi,  which  is  probably  a  dioxy-derivative  of  coumarin:   C6H2(OH)2 

\0 CO 

Amygdalin — C20'H.27N011 — exists  in  the  bitter  almond,  in  the  ker- 
nels of  peach-  and  plum-pits,  apple-  and  pear-seeds,  and  a  great 
variety  of  other  plants.  It  crystallizes  in  colorless  prisms  with  3  Aq, 
easily  soluble  in  water,  insoluble  in  ether,  odorless,  and  bitter.  It  is 
decomposed  by  dilute  mineral  acids,  or  by  emulsin,  into  two  mole- 
cules of  glucose  and  one  each  of  benzoic  aldehyde  and  hydrocyanic 
acid: 

C20H27N011+2H20=2C6H70(OH)5+C6H5.CHO+CNH 

By  the  action  of  alkalies,  particularly  by  heating  with  Ba(OH)2, 
amygdalin  yields  amygdalic  acid,  C20H28013,  of  which  amygdalin  ap- 
pears to  be  the  nitrile:  C6H70(OH)4.O.C6H70(OH)3.O.CH(CX6H5)CN 
and  this,  on  splitting  off  of  the  sugar,  first  forms  the  nitrile  of  man- 
delic  acid:  C6H5.CHOH.CN,  the  subsequent  decomposition  of  which 
into  C6H5.CHO  and  HCN  is  evident.  Amygdalin  itself  is  non-poi- 
sonous, but  its  ready  decomposition,  with  formation  of  the  extremely 
poisonous  hydrocyanic  acid,  is  a  prolific  source  of  cyanic  poisoning. 

Coniferin — C,flH22O8 — is  a  glucoside  occurring  in  the  inner  bark  (cambium) 
of  coniferous  plants,  and  in  asparagus  and  the  sugar-beet.  It  crystallizes  in 
silky,  white  needles,  sparingly  soluble  in  water,  faintly  bitter.  With  phenol 
and  concentrated  hydrochloric  acid  it  assumes  an  intense  blue  color  (pine-shaving 
reaction).  It  is  decomposed  by  emulsin  into  glucose  and  coniferyl  alcohol,  which 

is  a  hydroxyl-oxymethyl  cinnamyl   alcohol:    CH3J^Q^C6H3.CH:CH.CH2OH.     By 

oxidation  with  chromic  acid  it  forms  glucovanillin,  CaHn05.O.C6H3(OCH3)CHO, 
which  is  decomposed  by  emulsin  into  glucose  and  vanillin:  methylprotocatechuic 
aldehyde.  Glucovanillin,  containing  an  aldehyde  group,  forms  a  crystalline  com- 
pound with  phenylhydrazine,  and  an  oxime.  By  further  oxidation  it  forms 
glucovanillic  acid,  and  by  reduction,  the  corresponding  alcohol. 

Daphnin,  C18H18OB,  occurs  in  the  bark  of  Daphne  mezereum,  and  other 
species  of  Daphne.  It  crystallizes  in  colorless  prisms,  bitter  and  astringent, 
sparingly  soluble  in  water  and  in  ether,  soluble  in  alcohol.  It  is  colored  bluish 
by  ferric  chloride.  It  is  decomposed  into  glucose  and  daphnetin,  C9H8O4,  isonicric 
with  aesculetin  (above).  Daphnetin  has  been  shown  to  be  a  dioxycoumarin, 
having  the  hydroxyls  in  the  positions  1,  2,  by  its  synthesis  by  condensation  of 
pyrogallol  and  malic  acid: 

C«H,  ( OH )  8(i-iwj)  +COOH.CH2.CHOH.COOH=H.COOH+2H20+ 

/O(3>— CO 
C,H2(OH)2(i2> 

\CH(*):CH 


GLUCOSIDES  363 

Digitalis  Glucosides. — The  active  substance  of  digitalis  consists, 
in  part  at  least,  of  a  glucoside,  or  glucosides,  probably  accompanied 
by  products  of  decomposition,  but  the  chemistry  of  these  compounds 
requires  further  investigation.  Digitonin,  C27H44013(  ?),  is  the  most 
abundant  constituent  of  the  ' '  amorphous  digitalins, ' '  and  has  little  or 
no  therapeutic  value.  It  is  an  amorphous,  white  solid,  very  sol- 
uble in  water,  which  crystallizes  from  its  alcoholic  solutions.  It  is 
decomposed  by  dilute  hydrochloric  acid  into  digitone'in,  or  digito- 
genin,  C15H2404,  glucose  and  galactose.  Digitalin,  (C5H802)n(  ?), 
separates  in  amorphous  or  nodular  masses  from  its  alcoholic  solution. 
On  decomposition  it  yields  digitaliresin,  C16H2202,  glucose  and  digi- 
talose,  C7H1405.  It  has  the  physiological  action  of  digitalis  upon  the 
heart,  and  is  the  principal  constituent  of  "Homolle's  digitalin." 
Digitoxin,  C21H3207(?),  crystallizes  in  fine  needles,  insoluble  in 
water,  soluble  in  hot  alcohol  and  in  chloroform.  It  is  the  most 
actively  poisonous  of  the  digitalis  glucosides,  and  is  the  chief  con- 
stituent of  "Nativelle's  digitalin."  Digitalin  gives  a  color-reaction 
which  is  not  given  by  digitoxin :  it  forms  a  golden-yellow  or  brownish 
solution  with  concentrated  H2S04,  which  becomes  violet-red  by  the 
action  of  bromine  vapor. 

Toxicology. — The  prominent  symptoms  of  poisoning  by  digitalis  are: 
nausea,  and  occasionally  vomiting;  sometimes  colic  and  diarrhea;  after  two  or 
three  hours,  marked  diminution  in  the  frequency  of  the  pulse,  which  may  fall  to 
40  or  even  25;  dyspnea,  attended  by  a  sense  of  oppression  in  the  chest  and 
coldness  of  the  extremities;  headache,  vertigo,  and  tendency  to  sleep;  usually 
attacks  of  synocope  occur,  provoked  sometimes  by  the  slightest  movement  of  the 
patient;  death  is  generally  by  syncope,  sometimes  after  several  hours  of  coma 
succeeded  by  convulsions. 

The  treatment:  The  patient  must  be  kept  strictly  in  the  recumbent  posi- 
tion. The  stomach  should  be  washed  out  with  infusion  of  tea  by  the  stomach 
tube.  Stimulants  should  be  given. 

Indican — C26H31N017 — is  a  glucoside  occurring  in  the  indigo 
plant.  It  is  a  yellow  or  light  brown  syrup,  which  cannot  be  dried 
without  decomposition,  bitter  and  disagreeable  in  taste,  acid  in  re-, 
action,  and  soluble  in  water,  alcohol  and  ether.  It  is  very  prone  to 
decomposition.  Even  slight  heating  decomposes  it  into  leucine, 
indicanin,  C20H23N012,  and  indiglucin,  C6H1006.  A  characteristic 
decomposition  is  that  by  which  it  yields  indigo-blue  and  indiglucin, 
along  with  other  products : 

2C20H31N017+4H20=C16H10N202+6C6H1006 

The  substance  found  in  the  urine,  and  erroneously  called  "indi- 
can,"  is  not  a  glucoside,  but  is  potassium  indoxyl  sulphate:  K.C8H6- 
N.S04  (see  p.  417). 

Myronic  Acid,  C,0Hi9NS2010,  exists  in  the  seeds  of  black  mustard  as  its  K 
salt,  which  is  hydrolyzed  by  myrosin  into  glucose,  allyl  isothiocyanate  and 
KHS04. 


364  TEXT-BOOK   OF   CHEMISTRY 

Phloridzin,  C21H?4O10,  occurs  in  the  root-bark  of  apple  and  other  fruit  trees. 
When  ingested  it  causes  glycosuria.  It  is  hydrolyzed  by  boiling  with  dilute 
acids,  or  even  with  water,  into  a  crystalline,  dextrogyrous  hexose,  phlorose, 
and  phloretin,  C]5H14O5,  which  is  further  decomposed  by  hot  alkalies  into  phloro- 
glucin  and  phloretic,  or  p-oxyhydratropic  acid:  C«H4 ( OH )  .C2H4.COOH. 

Salicin — C13H1807 — occurs  in  willow  bark.  It  is  a  white,  crys- 
talline substance,  insoluble  in  ether,  soluble  in  water  and  in  alcohol, 
very  bitter  in  taste.  Concentrated  H2S04  colors  it  intensely  red,  the 
color  being  discharged  by  addition  of  water.  It  is  decomposed  by 
emulsin,  by  saliva,  or  by  mineral  acids  into  glucose  and  saligenin. 
When  taken  into  the  economy  it  is  converted  into  salicylic  aldehyde 
and  acid,  which  are  eliminated  in  the  urine.  Populin,  a  glucoside 
from  poplar  bark,  is  benzoyl-salicin. 

Santonin — C15H1803  is  the  active  glucoside  of  the  Artemisia  pauci- 
flora.  It  is  used  as  an  anthelmintic. 

Solanin — C42H87N015(  ?) — is  a  glucoside  having  basic  properties, 
an  alkaloid-glucoside,  occurring  in  a  variety  of  plants  of  the  genus 
Solanum.  It  crystallizes  in  white,  silky  needles,  acrid  and  bitter  in 
taste,  insoluble  in  water,  sparingly  soluble  in  alcohol  and  in  ether.  By 
the  action  of  hot  dilute  acids  it  is  decomposed  into  glucose  and  a 
basic  substance,  solanidin. 


ANHYDRIDES  AND  ACID  HALIDES. 

The  aromatic  acidyls  form  oxides,  or  anhydrides,  and  haloid  com- 
pounds, corresponding  to  those  of  the  aliphatic  acidyls,  and  produced 
by  similar  methods. 

Benzoic  Anhydride — (C6H5.CO)20 — is  formed  from  benzoyl  chlor- 
ide by  several  methods :  as  by  a  reaction  between  benzoyl  chloride  and 
silver  benzoate: 

C6H5.CO.Cl+C6H5.COOAg=(C6H5.CO)20+AgCl 

It  is  a  crystalline  solid,  f.  p.  42°,  b.  p.  360°. 

Phthalic  Anhydride — C6H4(CO)2:0 — being  formed  from  a  dicar- 
boxylic  acid,  is  produced  from  a  single  molecule  of  the  acid,  with 
elimination  of  H20.  It  is  formed  by  fusing  phthalic  acid.  It  sub- 
limes in  needles;  f.  p.  128°;  sparingly  soluble  in  cold  water,  soluble 
in  hot  water,  with  regeneration  of  the  acid,  very  soluble  in  alcohol 
and  in  ether.  It  combines  with  phenols  to  form  phthaleins. 

Salicylic    Anhydride— Salicylide— C6H4/g^g\C6H4    (probably) 

—is  formed  by  the  action  of  phosphorus  oxychloride  on  salicylic  acid, 
It  forms  a  crystalline  compound  with  chloroform  in  which  the  latter 
behaves  as  water  of  crystallization :  (C7H402)4.2CHC13,  which  is 
utilized  to  purify  that  anesthetic. 

Benzoyl   Chloride— CeH5.CO.Cl— was   the  first   obtained   of   the 


AROMATIC   SULPHUR-DERIVATIVES — SULPHONIC   ACIDS  365 

acidyl  halides.    It  is  formed  by  the  action  of  hydrochloric  acid  upon 
benzoic  acid,  in  presence  of  phosphorus  pentoxide: 

C6H5.COOH+HC1=C6H5.CO.C1+H20 
Or  by  the  action  of  chlorine  upon  benzoic  aldehyde: 

C6H5.CHO+C12=HC1+C6H5.CO.C1 

Or,  along  with  acetyl  chloride,  by  the  action  of  chlorine  upon 
benzyl  acetate: 

CH3.COO(CH2.C6H5)+2C12=:C6H5.CO.C1+CH3.CO.C1+2HC1 

The  two  chlorides  are  separated  by  fractional  distillation. 
Benzoyl  chloride  is  a  colorless  liquid;  b.  p.  198°;  having  a  pene- 
trating odor.     With  silver   (or  mercuric)   cyanide  it  forms  benzoyl 
cyanide : 

C6H5.CO.Cl+AgCN=C6H5.CO.CN+AgCl 

It  acts  readily  upon  the  polyatomic  alcohols  and  upon  the  hexoses, 
when  shaken  with  their  solutions  in  presence  of  caustic  soda.     With 
the  hexoses  pentabenzoyl  compounds  are  formed,  and  crystallize  out: 
CHO.C5H6(OH)5+5C6H5.CO.C1=CHO.C5H6(O.CO.C6H5)5+5HC1 

This  is  a  reaction  utilized  for  the  isolation  of  hexoses  and  poly- 
atomic alcohols.  A  similar  reaction,  similarly  utilized,  occurs  with 
the  diamines,  in  which  insoluble,  crystalline,  dibenzoyl  compounds 
are  formed : 

C2H4(NH2)2+2C6H5.CO.C1=C2H4(NH.CO.C6H5)2+2HC1 

AROMATIC    SULPHUR-DERIVATIVES— SULPHONIC    ACIDS. 

Many  thio-aromatic  compounds  are  known,  as  thiophenol,  C6H5.- 
SH,  phenyl  sulphide,  (C6H5)2S,  and  thio-benzoic  acid,  C6H5.COSH. 
But  the  most  important  of  the  aromatic  compounds  containing  sul- 
phur are  the 

Sulphonic  Acids  (p.  286),  monobasic  acids  containing  the  group 
S03H,  formed  by  the  union  of  the  aromatic  hydrocarbon,  or  deriva- 
tive, with  H2S04  with  elimination  of  OH  from  the  acid  and  H  from 
the  aromatic  compound,  a  process  called  "sulphonation":  C6H6+H2- 
S04=C6H5.S03H-|-H20.  The  aromatic  and  polybenzenic  sulphonic 
acids  are  formed  much  more  readily  than  the  corresponding  aliphatic 
acids,  and,  being  acid  and  soluble,  are  largely  used  as  dyes.  They 
are  usually  produced  by  the  action  of  fuming  H2S04  upon  the  aro- 
matic compound,  with  or  without  the  aid  of  heat. 

The  sulphonic  acids  are  not  decomposed  by  boiling  with  alkaline 
solutions,  but  their  salts,  when  fused  with  caustic  alkalies,  yield 
phenols : 

C6H5.S03K+KOH=C6H5.OH+K2S03 

Distilled  with  potassium  cyanide  they  yield  nitriles : 
C6H5.S03K+KCN=C6H5.CN+K2S03 


366  TEXT-BOOK   OF   CHEMISTRY 

By  the  action  of  PC15  they  are  converted  into  their  chlorides, 
e.g.,  C6H5.S02C1,  which  may  be,  in  turn,  converted  into  sulphinic 
acids,  sulphones,  etc.  They  are  easily  soluble  in  water,  and  may  be 
separated  from  their  solutions,  as  sodium  salts,  by  the  addition  of 
NaCl. 

Benzene-monosulphonic  Acid — C6H5.S03H — is  formed  by  dis- 
solving benzene  in  weak  fuming  sulphuric  acid  at  a  slightly  elevated 
temperature,  and  diluting  with  H20.  It  crystallizes  in  extremely 
soluble,  deliquescent  plates  with  ll/2  Aq.  By  the  action  of  PC15  upon 
benzene  monosulphonates,  benzene  sulphochloride  is  produced: 
C6H5.S03K+PC15=C6H5.S02C1+KC1+POC13 

This  is  an  oily  liquid,  b.  p.  246°,  which  is  a  valuable  reagent  for 
amines  and  amido  compounds. 

Three   benzene-disulphonic   acids — C6H4(S03H)2 — ortho-,   meta- 
and    para-,    are    known,    also    one    benzene-trisulphonic    acid  — 
C6H3(S03H)3. 

Three  toluene-sulphonic  acids — C6H4(CH3).S03H — ortho-,  meta- 
and  para-,  have  been  obtained.  By  the  action  of  a  mixture  of  ordi- 
nary and  fuming  sulphuric  acids  upon  toluene  at  a  temperature  not 
exceeding  100°,  a  mixture  of  the  ortho-  and  para-  acids  is  produced. 
When  this  is  treated  with  PC15,  it  is  converted  into  a  mixture  of  para- 
and  ortho-toluene  sulphonic  chlorides— C6H4.CH3.S02C1.  The 
ortho-chloride,  when  acted  on  by  dry  ammonia  and  ammonium  car- 
bonate, is  converted  into  ortho-toluene  sulphamide — CJEI^CHg.- 
S02NH2.  This  product,  when  oxidized  by  potassium  permanganate, 
is  converted  into  benzoyl-sulphonic  imide — CfiH4.CO.S02NH— 
benzosulphinidium,  or  benzosulphinide  or  saccharin  of  the  U.  S.  P. 
— an  odorless,  crystalline  powder,  having  great  sweetening  power, 
its  sweet  taste  being  still  detectable  in  a  dilution  of  1-50,000.  Spar- 
ingly soluble  in  water  and  in  ether,  readily  in  alcohol.  Its  solutions 
are  acid  in  reaction.  When  heated  with  Na2C03  it  is  carbonized  and 
gives  off  the  odor  of  benzene.  It  is  not  attacked  by  H2S04. 

Another  series  of  sulphonic  derivatives  is  obtained  from  the 
phenols.  Among  them  is: 

Ortho-phenol  sulphonic  Acid — Sozolic  acid — Aseptol — C6H4- 
(OH)  (1)  (S03H)  (2)  which  is  prepared  by  the  action  of  cold  concen- 
trated H2S04  upon  phenol.  It  is  a  reddish,  syrupy  liquid,  soluble  in 
H20  in  all  proportions,  has  a  faint  and  not  disagreeable  odor.  It 
prevents  fermentation  and  putrefaction,  and  is  a  non-poisonous,  non- 
irritant  antiseptic.  The  salts  of  this  and  the  corresponding  para- 
and  meta-acids  have  been  used  as  antiseptics  and  insecticides,  under 
the  name  of  sulphocarbolates  or  phenol-sulphonates,  e.  g.  Sodii 
phenolsulphonas  (U.  S.  P.). 

Phenylsulphuric  Acid— Monophenyl  Sulphate—  CO^Q/  S02— iso- 
meric  with  the  phenol  monosulphonic  acids,  and  corresponding  to 


NITROGEN- CONTAINING   DERIVATIVES   OF   BENZENE  367 

the  acid  ethyl  sulphuric  ester,  ethylsulphuric  acid,  is  the  acid  phenyl 
sulphuric  ester  which  exists  in  its  salts  in  the  urine,  and  is  the  type 
of  numerous  similar  compounds,  the  " ester  sulphates,"  which  are 
formed  in  the  economy  from  substances  containing  a  phenolic  hy- 
droxyl.  The  potassium  salt  of  the  acid  is  obtained  by  the  action  of 
potassium  pyrosulphate  upon  potassium  phenate: 

S207K2+C6H5.OK=C6H5.O.S03K+S04K2 
The  free  acid  decomposes  rapidly. 

NITROGEN-CONTAINING  DERIVATIVES  OF  BENZENE. 

The  nitrogen  derivatives  of  benzene  are  very  numerous,  of  great 
variety  of  structure,  and  include  among  their  number  several  sub- 
stances of  great  industrial  value. 

They  may  be  classified  into  five  principal  groups:  (1)  The  nitro- 
compounds,  derived  from  other  benzenic  compounds  by  substitution 
of  N02  for  H,  and  the  nitroso-compounds,  containing  the  nitroso 
group,  NO;  (2)  the  hydroxylamine  compounds,  containing  the 
group  — N\HH'  an(*  the*r  nitroso  derivatives;  (3)  the  amido-  and 
imido-compounds,  containing  NH2  and  NH,  the  aromatic  amines, 
amides,  and  amido-acids,  and  their  derivatives;  (4)  the  azo-  and 
diazo-compounds  and  their  numerous  derivatives,  containing  the 
grouping  — N=N — ;  (5)  the  hydrazines,  containing  the  grouping 
=N — N=,  and  their  nitroso  derivatives. 

NITRO-  AND  NITROSO-COMPOUNDS 

Nitro-benzenes. — These  contain  the  nitro  group  directly  attached 
to  the  carbon  of  the  benzene  ring.  They  are  produced  by  the  action 
of  fuming  HN03,  or  a  mixture  of  HN03  and  H2S04,  upon  the  hydro- 
carbons : 

C6H6+HN03=C6H5.N02+H20 

They  are  yellow  liquids,  sparingly  soluble  in  water.  Their  most 
important  property  is  their  ready  reduction,  first  to  hydroxylamine 
compounds : 

C6H5.N02+2H2=C6H5.NH.OH+H20 

and  then  to  amicto-compounds : 

C6H5.NH.OH+H2=C6H5.NH2+H20 

Mono-nitro-benzene — Nitro-benzol — Nitro-benzene — Essence  of 
Mirbane — CGH5.N02 — is  obtained  by  the  moderated  action  of  fuming 
HN03,  or  of  a  mixture  of  HN03  and  H2S04  on  benzene. 

It  is  a  yellow,  sweet  liquid,  with  an  odor  of  bitter  almonds;  sp. 
gr.  1.209  at  15°;  boils  at  213°;  almost  insoluble  in  water;  very 
soluble  in  alcohol  and  in  ether.  Concentrated  H2S04  dissolves,  and, 
when  boiling,  decomposes  it.  Boiled  with  fuming  HN03  it  is  con- 


368 


TEXT-BOOK   OF    CHEMISTRY 


verted  into  dinitro-benzenes.  It  is  converted  into  aniline  by  re- 
ducing agents. 

It  has  been  used  in  perfumery  as  artificial  essence  of  bitter  al- 
monds; but  as  inhalation  of  its  vapor,  even  largely  diluted  with  air, 
causes  headache,  drowsiness,  difficulty  of  respiration,  cardiac  irregu- 
larity, loss  of  muscular  power,  convulsions,  and  coma,  its  use  for  that 
purpose  is  to  be  condemned.  Taken  internally,  it  is  an  active  poison. 

Nitro-benzene  may  be  distinguished  from  oil  of  bitter  almonds 
(benzoic  aldehyde)  by  H2S04,  which  does  not  color  the  former;  and 
by  the  action  of  acetic  acid  and  iron  filings,  which  convert  nitro- 
benzene into  aniline,  whose  presence  is  detected  by  the  reactions  for 
that  substance  (p.  371). 

Dinitrobenzenes. — The  three  dinitrobenzenes  are  produced  by 
boiling  the  mono-nitro  compound  with  fuming  HN03.  The  meta- 
compound  predominates,  and  may  be  separated  by  fractional  crystal- 
lization from  alcohol.  It  crystallizes  in  plates,  fusible  at  90°,  and 
is  used  in  the  preparation  of  certain  dyes,  and  of  explosives,  such 
as  roburite,  sicherheit,  etc.  The  gases  resulting  from  such  explo- 
sives are  poisonous. 

Nitrotoluenes. — C6H4.CH3.N02 — The  o-  and  p-compounds  are  pro- 
duced together  by  nitration  of  toluene,  and  exist  in  the  commercial 
nitro-benzene.  They  may  be  separated  by  fractional  distillation,  the 
o-compound  boiling  at  218°,  and  the  p-  at  230°.  By  reduction  they 
yield  the  corresponding  toluidines,  largely  used  in  the  color  industry. 

By  the  action  of  HN03  on  nitrobenzene,  meta-compounds  are  ob- 
tained principally : 


NO, 


NO, 


+  HNO,    = 


+H,0 


NO2 


And  by  action  of  HN03  on  toluene,  we  obtain  a  mixture  of  ortho- 
and  para-nitrotoluene : 


-f2HNO,     = 


NO, 


+2H,0 


When  the  first  substituted  group  contains  a  double  or  triple  link- 
age as  in  N02,  COOH,  CHO,  COCH3,  CN,  a  second  introduced  group 


NITROGEN-CONTAINING   DERIVATIVES   OF  BENZENE 


369 


occupies  the  meta-position  preferably.  But  when  the  first  substi- 
tuted group  contains  only  single  linkages  as  in  Cl,  Br,  I,  CH3,  NH2, 
OH,  mixtures  of  ortho-  and  para-  groups  are  formed. 

Thus  by  the  action  of  Cl  on  benzoic  acid  the  meta-compound  alone 

is  formed: 

COOH  COOH 


+  C12    = 


+HC1 


If  ortho-  or  para-compound  is  desired,  circuitous  methods  must 
be  followed.     Thus,  for  ortho  acid,  starting  from  phenol: 


OH 


-f  CC14  +  4KOH    = 


COOH 


COOH 


+4KC1+2H.O,  and 


COOH 


+POC1.+HC1 


Nitro-phenols  —  Mononitro-phenols  —  C6H4(N02)  OH  —  (1—2) , 
(1—3)  and  (1—4)  are  formed  by  the  action  of  HN03  on  C6H5.OH. 
The  ortho  compound  (1 — 2)  crystallizes  in  large  yellow  needles,  spar- 
ingly soluble,  and  capable  of  distillation  with  steam.  The  meta  and 
para  compounds  are  both  colorless,  non-volatile,  crystalline  bodies. 
Methyl  chloride  converts  nitrophenols  into  the  corresponding  nitro- 
anisols,  C6H4.OCH3.N02,  and  ethyl  iodide  into  nitrophenetols,  C6H4- 
OC2H5.N02,  which  by  reduction  yield  anisidines  and  phenetidines 
(p.  373).  Two  dinitro-phenols,  (C6H3.OH(N02)2(24),  and  C6H3.OH- 
(N02)2  (2-6)  are  obtained  by  the  action  of  strong  nitric  acid  on  phenol 
or  on  ortho-  or  para-mononitro  phenol.  They  are  both  solid,  crystal- 
line substances,  converted  by  further  nitration  into  picric  acid. 

Trinitro-phenols— C6H2(N02)3OH.— Two  are  known;   (1)  Picric 


acid — Carbazotic  acid — Trinitro-phenic  acid — (N02)  in  2- 


It 


is  formed  by  nitration  of  phenol,  or  of  1 — 2 — 4  or  1 — 2 — 6  dinitro- 
phenols,  and  also  by  the  action  of  HN03  on  indigo,  silk,  wool,  resins, 
etc.  It  crystallizes  in  yellow  plates  or  prisms,  odorless,  intensely 
bitter;  acid  in  reaction;  sparingly  soluble  in  water,  very  soluble  in 


370  TEXT-BOOK   OF    CHEMISTRY 

alcohol,  ether,  and  benzene;  it  fuses  at  122.5°,  and  may,  if  heated 
with  caution,  be  sublimed  unchanged;  but,  if  heated  suddenly  or  in 
quantity,  it  explodes  with  violence.  It  behaves  as  a  monobasic  acid, 
forming  salts,  which  are  for  the  most  part  soluble,  yellow,  crystal- 
line, and  decomposed  with  explosion  when  heated. 

Picric  acid  colors  silk  and  wool  yellow.  It  is  used  as  a  reagent 
for  the  alkaloids,  with  many  of  which  it  forms  crystalline  precipitates, 
as  it  also  does  with  many  other  substances.  It  is  sometimes  added 
to  beer  and  to  other  food  articles,  to  communicate  to  them  either  a 
bitter  taste  or  a  yellow  color.  Its  solutions  give  yellow,  crystalline 
precipitates  with  K  salts ;  green  precipitates  with  ammoniacal  CuS04 ; 
and  an  intense  red  color  when  warmed  with  alkaline  KCN  solution. 
It  is  poisonous, 

Nitro-cresols— C6H3.CH3.OH.N02— The  o-  and  p-  compounds  are 
known.  They  are  readily  converted  into  the  corresponding  dinitro 
compounds,  C6H2.CH3.OH.(N02)2.  The  2-6  dinitro  compound  is 
used  as  a  dye  in  the  form  of  its  sodium  salt,  under  the  name  Victoria 
orange,  or  saffron  surrogate.  It  is  poisonous. 

The  nitroso-phenols  are  obtained  by  the  action  of  nitrous  acid 
upon  the  phenols;  or  by  the  action  of  hydroxylammonium  chloride 
upon  the  quinones. 

p-Nitroso-phenol  —  Quinoxime  —  C6H4.(OH)(1)(NO)(4),     or     C6- 

£J       I    crystallizes  in  needles,  and  explodes  when  heated.    Dinitroso- 

\N.OH 

resorcinol—  C6H2(OH)2(13)(NO)2(46)  is  a  brown,  explosive  substance, 
used  as  a  green  dye,  solid  green. 

Nitro-acids,  such  as  o-,  m-,  and  p-nitro-benzoic  acids,  C6H4- 
COOH.N02,  etc.,  are  known.  They  yield  amido-acids  by  reduction. 

HYDROXYLAMINE  COMPOUNDS. 

Compounds  derived  from  hydroxylamine  by  substitution  of  phenyl 
or  alkyl-phenyls  for  extra-hydroxyl  hydrogen  are  formed  as  inter- 
mediate products  of  reduction  of  the  nitro-benzenes  (p.  367). 

Phenylhydroxylamine — C6H5.N/°H — is  an  intermediate  product 

of  reduction  between  nitro-benzene  and  amido-benzene : 
C6H5.N02H-2H2=C6H5.N/OH  +H20,  and 

C6HrN02+3H2=C6H5.NH2+2H20 

It  is  readily  oxidized  to  nitroso-benzene  and  other  products,  and 
it  reduces  Fehling's  solution  and  ammoniacal  AgN03  solution.    Min- 
eral acids  cause  its  intramolecular  rearrangement  to  p-amido-phenol : 
C0H5.N<£H=C0H4(OH)(1)(NH2)(4) 

*  /OH 

With  nitrous  acid  it  forms  a  nitroso  derivative:  C6H5.Nx^()  . 

It  is  a  crystalline  solid;  f.  p.  81°;  and  forms  a  crystalline,  colorless 
hydrochloride. 


NITROGEN-CONTAINING  DERIVATIVES  OF  BENZENE  371 


AMIDO-COMPOUNDS. 

The  amido-benzenes  are  the  counterparts  of  the  aliphatic  primary 
monamines.  They  are  obtained  by  reduction  of  the  corresponding 
nitro-compounds.  The  reaction  is,  with  moderate  reduction,  not  so 
simple  as  is  expressed  by  the  equation: 

C6H5.N02+3H2=C6H5.NH2+2H20 

but  several  important  intermediate  products  are  formed    (p.   367, 
and  above). 

Aniline — Amido-benzene — Amido-benzol — Phenylamine  —  C6H5.- 
NH2 — exists  in  small  quantity  in  coal-tar,  and  is  one  of  the  products 
of  the  destructive  distillation  of  indigc.  It  is  prepared  by  the  re- 
duction of  nitro-benzene  by  hydrogen: 

C6H5.(N02)+3H2=C6H5(NH2)+2H20  (see  above) 

the  hydrogen  being  liberated  in  the  nascent  state  in  contact  with 
nitro-benzene  by  the  action  of  iron  filings  on  acetic  acid. 

Pure  aniline  is  a  colorless  liquid;  has  a  peculiar,  aromatic  odor, 
and  an  acrid,  burning  taste;  sp.  gr.  1.02  at  16°;  boils  at  184.8°; 
crystallizes  at  — 8°;  soluble  in  31  parts  of  cold  water,  soluble  in 
all  proportions  in  alcohol,  ether,  carbon  bisulphide,  etc.  When  ex- 
posed to  air  it  turns  brown,  the  color  of  the  commercial  "aniline 
oil, ' '  and,  finally,  resinifies.  It  is  neutral  in  reaction.  Oxidizing 
agents  convert  it  into  rosaniline,  C20H19N3,  from  which  blue,  violet, 
red,  green,  or  black  derivatives  are  obtained.  Cl,  Br,  and  I  act  upon 
it  violently  to  produce  products  of  substitution.  Concentrated  H2S04 
converts  it,  according  to  the  conditions,  into  sulphanilic,  or  p-amido- 
benzone  sulphonic  acid,  C6H4(NH2)(1),  (S03H)(4),  or  disulphanilic 
acid,  or  aniline  2-4  disulphonic  acid,  C6H3(NH2)(1),(S03H)2(2  4). 
With  acids  it  unites,  after  the  manner  of  ammonia,  to  form  salts, 
most  of  which  are  crystallizable,  soluble  in  water,  and  colorless,  al- 
though by  exposure  to  air,  especially  if  moist,  they  turn  red.  The 
sulphate  has  been  used  medicinally.  Potassium  permanganate 
oxidizes  it  to  nitro-benzene.  Heated  with  H2S04  and  glycerol  it  pro- 
duces quinoline,  and  substituted  quinoline  may  be  obtained  by  a 
similar  reaction  from  substituted  anilines. 

With  alkyl  magnesium  iodides  and  bromides,  aniline  and  methyl 
aniline  produce  the  Meunier  compounds :  C6H5.NH.MgBr.  and  C6H5.- 
N(CH3).MgBr.  The  former  reacts  with  aldehydes  to  produce  imines: 

K.CHO+C6H5.NH.MgBr=R.CH(O.MgBr).NH.C6H5  and 
R.CH  ( O.MgBr )  .NHC6H5=R.CH  :N.C6H5+HO.MgBr. 

Aniline  itself,  when  taken  in  the  liquid  form  or  by  inhalation,  is 
an  active  poison,  producing  symptoms  similar  to  those  caused  by 


372  TEXT-BOOK   OP   CHEMISTRY 

nitro-benzene  (p.  368).      Its  salts,  if  pure,  seem  to  have  but  slight 
deleterious  action. 

Aniline  may  be  recognized  by  the  following  reactions:  (1)  With 
a  nitrate  and  H2S04:  a  red  color;  (2)  cold  H2SO4  does  not  color  it 
alone;  on  addition  of  potassium  dichromate,  a  fine  blue  color  is 
produced,  which,  on  dilution  with  water,  passes  to  violet,  and,  if  not 
diluted,  to  black.  (3)  With  calcium  hypochlorite  :  a  violet  color; 
(4)  heated  with  cupric  chlorate:  a  black  color;  (5)  heated  with  mer- 
curic chloride:  a  deep  crimson  color;  (6)  in  very  dilute  solution 
(1:250,000),  aniline  gives  a  rose  color  with  chloride  of  lime,  followed 
by  ammonium  sulphydrate. 

Toluidines—  CeH4(CH3)  (NH2)—  Three  toluidines,  o-,  m-,  and  p-,  are 
known  as  the  superior  homologues  of  aniline.  They  occur  in  commercial  aniline 
and  play  an  important  part  in  the  production  of  aniline  colors. 

Xylidines  —  Amido-xylenes  —  C6H3(CH3)2(NH2).  —  Six  compounds  of  this 
composition  are  known  :  two  derived  from  ortho-xylene,  three  from  meta-xylene, 
and  one  from  para-xylene.  Five  of  them  exist  in  commercial  xylidine. 

The  toluidines  and  xylidines  yield  products  of  substitution  and  addition 
similar  to  those  of  aniline. 


Carbodiimidcs  are  substances  having  the  general  formula  Cv^R,  in  which 
RR  are  two  univalent  radicals,  usually  belonging  to  the  aromatic  series.  They 
are  prepared  from  the  sulphurei'des,  by  loss  of  the  elements  of  carbon  oxysul- 
phide,  COS,  by  the  action  of  heat  or  of  oxidants. 

Anilides.  —  These  are  compounds  in  which  one  of  the  H  atoms  of 
the  amido  group  has  been  replaced  by  an  acid  radical.  Or  they 
may  also  be  considered  as  amides,  whose  remaining  hydrogen  has 
been  more  or  less  replaced  by  phenyl,  C6H5. 

Acetanilide  —  Antifebrine  —  Phenyl-acetamide  —  C6H5(NH.CO.- 
CH3)  —  is  obtained  either  by  heating  together  aniline  and  glacial  acetic 
acid  for  several  hours,  or,  better,  by  the  action  of  acetyl  chloride 
on  aniline.  It  forms  colorless,  shining,  crystalline  scales;  fuses  at 
112.5°,  and  volatilizes  unchanged  at  295°.  It  is  sparingly  soluble  in 
cold  water,  soluble  in  hot  water  and  in  alcohol. 

When  acetanilide  is  heated  with  an  equal  weight  of  ZnCl2,  flav- 
aniline,  a  colored  substance  having  a  fine  green  fluorescence,  and 
soluble  in  warm  dilute  HC1,  is  produced. 

Acetanilide  and  its  derivatives  in  the  urine  respond  to  the  indo- 
phenol  reaction:  Boiled  a  few  minutes  with  HC1,  a  colorless 
solution  is  formed,  which,  on  addition  of  H20  and  solution  of  phenol 
in  chlorinated  lime  solution,  assumes  a  turbid,  dirty  red  color,  and 
on  addition  of  ammonia  an  indigo-blue  color. 

By  the  further  substitution  of  a  group  (CH3)  in  acetanilide,  methyl- 
acetanilide,  or  exalgine,  C6H5.N(CH3).C2H30,  is  produced.  It  is 
formed  by  the  action  of  methyl-iodide  upon  sodium  acetanilide, 
CflH5.NNa.C2H30.  It  is  a  crystalline  solid,  sparingly  soluble  in  H20, 
readily  in  dilute  alcohol.  Its  odor  is  faintly  aromatic. 


NITROGEN-CONTAINING   DERIVATIVES  OF  BENZENE  373 

The  "aniline  dyes"  now  so  extensively  used,  even  those  made 
from  aniline,  are  not  compounds  of  aniline,  but  are  salts  of  bases 
formed, from  it,  themselves  colorless,  called  rosaniline. 

Phenylamines — Phenylenediamines,  etc. — Aniline  is  the  simplest 
representative  of  a  large  class  of  substances.  It  may  be  considered 
as  benzene  in  which  H  has  been  replaced  by  NH2,  thus:  C6H5.NH2. 
Its  superior  homologues,  derivable  from  the  superior  homologues  of 
benzene,  each  have  at  least  three  isomeres,  ortho-,  meta-,  and  para-, 
according  to  the  orientation  of  the  groups  NH2  and  CnHan+i.  Aniline 
may  also  be  considered  as  ammonia  in  which  H  has  been  replaced 

by  phenyl,  C6H5,  thus  being  a  primary  monamineCeS5  I N.     The  re- 

Jti2  ) 

maining  two  H  atoms  may  be  replaced  by  other  radicals  to  form  an 
almost  infinite  variety  of  secondary  and  tertiary  phenylamines,  pre- 
cisely as  in  the  case  of  the  aliphatic  monamines. 

Phenylcarbylamine — Phenyl  Isocyanide — Isobenzonitrile — C6H5.N :  C — is 
formed  when  chloroform  is  heated  with  aniline  and  caustic  potash  in  alcoholic 
solution  (p.  206).  It  is  a  liquid,  having  a  most  persistent,  disagreeable  odor. 
Nascent  hydrogen  converts  it  into  methyl  aniline.  Heated  to  220°,  it  is  con- 
verted into  its  isomere,  benzonitrile,  or  cyanobenzene,  CflH5.CN,  which  is  a 
liquid  having  an  odor  of  bitter  almonds;  also  formed  by  distilling  potassium 
benzene  sulphonate  with  potassium  cyanide. 

XQTT 

Amido-phenols — C6H4<'-^jj — Three  are  known,  ortho-,  meta-,  and  para-, 
obtained  by  the  action  of  reducing  agents  upon  the  corresponding  nitro-com- 
pounds.  Their  methylic  ethers,  C6H4\N]5  are  known  as  anisidines;  and 

their  ethylic  ethers,  C6H4\M£[2        as  phenetidines. 

By  the  action  of  glacial  acetic  acid  upon  paraphenetidine,  an  aceto-deriva- 
tive,  para-acetophenetidine,  C6H4(OC2H5)(1).(NH.C2H3O)W,  is  formed.  It  is 
used  as  an  antipyretic,  under  the  name  phenacetine,  and  is  a  colorless,  odor- 
less, tasteless  powder,  sparingly  soluble  in  H2O,  readily  soluble  in  alcohol,  fuses 
at  135°.  Its  hot  aqueous  solution  is  colored  violet,  changing  to  ruby-red,  by 
chlorine  water. 

Aromatic  acid  amides  are  formed  by  methods  similar  to  those  by  which 
the  aliphatic  amides  are  produced,  and  resemble  them  in  their  reactions  (p.  312). 
Thus  benzamide,  or  benzoyl  amide,  C6H5.CO.NH2,  is  formed  by  the  action  of 
benzoyl  chloride  upon  ammonia: 

C8HVCO.C1+NH3=HC1+C6H5.CO.NH2 

as  a  crystalline  solid,  fusible  at  130°,  or  by  the  action  of  urea  chloride  upon 
benzene  in  presence  of  aluminium  chloride: 

H2N.CO.Cl+C6H6=C6H5.CO.NH2-fHCl 

Two  formulae  of  benzamide  are  possible:  the  amide  formula,  C«H5.CO.NH2, 
and  the  imide  formula,  C6H5.COH:NH.  Derivatives  corresponding  to  each  are 
known. 

Phthalamide— C6H4/g°NH2'  phthalamic  acid,  GA^eo^.  and  phthali- 
mide,  C6H4/CO\NH  ape  0^taine^  from  phthalic  anhydride.  The  last  named 

may  be  indirectly  condensed,  through  its  imide  H,  with  the  tatty  acids  to  produce 
compounds  which  serve  as  starting  points  in  syntheses  of  diamido  fatty  acids. 
The  aromatic  amido-acids  greatly  exceed  the  aliphatic     (p.  321)   in  num- 
ber and  variety.    They  are  :  ( 1 )  Amido-phenyl  acids,  which  may  be  considered 


374 


TEXT-BOOK    OF    CHEMISTRY 


either  as  aromatic  acids,  in  which  a  ring  hydrogen  atom  (or  atoms)  has  been 
replaced  by  NH2;  or  as  aliphatic  acids,  in  which  amido-phonyl  (CaH4.NH,)' 
has  replaced  H  in  a  hydrocarbon  group;  (2)  phenyl-amido  acids,  considered 
either  as  aromatic  acids,  in  which  XH2  replaces  H  in  a  hydrocarbon  group  of  a 
lateral  chain,  or  as  amido-aliphatic  acids,  in  which  phcnyl  (C'0H6)'  has  been 
substituted  for  H  in  a  hydrocarbon  group;  (3)  anilido-acids  —  aliphatic  amido- 
acids  in  which  phenyl  has  been  substituted  for  H  in  NH2.  In  this  class  are 
included  the  anilides  of  the  dicarboxylic  acids  (p.  371),  e.g.,  oxanilic  acid, 


'  (4)  amic  acids  (p>  310))  derived  from  the  dicarboxylic 
aromatic  acids  by  substitution  of  NH2  for  OH  in  one  carboxyl  group.  Besides 
these  there  are  amido-acids  referable  to  1  and  3,  in  which  the  radical  benzoyl, 
CaH5.CO,  takes  the  place  of  phenyl,  C6H5.  The  structure  of  these  several  acids 
is  shown  by  the  following  formulae: 

CH2.COOH  CHa.CH(NH2).COOH       NH.CH  COOH 


NHa 


Amido-phenyl 
acetic   acid. 


^  Phenyl,  a  amido- 
propionic    acid. 


CONHa 


(3) 

a  Anilido- 
propionic  acid. 


Those  aromatic  amido-acids  in  which  the  amido  group  is  attached  to  the 
ring  do  not  yield  monochlor-acids  by  treatment  with  NOC1,  but  those  in  which 
the  NH2  is  in  a  lateral  chain  do,  as  do  also  the  amido-acids  of  the  acetic  and 
oxalic  series  (p.  323). 

Amido-phenyl  Acids,  of  which  anthranilic,  or  o-amido-benzoic  acid, 
C«H4(COOH)  (1  (NH2)(2),  is  the  type,  are  formed  by  reduction  of  the  correspond- 
ing nitro-benzoic  acids.  Nitrous  acid  converts  them  into  the  corresponding 
oxyacids.  Thus  anthranilic  acid  yields  salicylic  acid.  The  o-acids  exhibit  a 
great  tendency  to  the  formation  of  lactams,  some  of  which  are  indigo  deriva- 

/CH2.CO(i) 
tives,  as  oxindole,  the  lactam  of  o-amido-phenyl  acetic  acid,  C8H4 

and    dioxindole,  the    lactam    of    o-amido-mandelic    acid,    C6H4/^_ 
Isatin,  a  product  of  oxidation  of  indigo,  is  the  lactam  of  o-amido-benzoyl-formic 
/CO.CO(1) 

The  amido-cinnamic  acids  are  closely  related  to  quino- 


K2) 


acid,  C6H4v 

\ 

line. 

Phenyl-alanine,  is  a  phenyl-amido  acid:  p  phenyl-  a-amido-propionic 
acid  (formula  above),  which  exists  in  certain  lupines,  and  is  a  product  of  de- 
composition of  the  proteins.  Its  corresponding  p-oxyphenyl  derivative  is: 

Tyrosine— p-Oxyphenyl  alanine—  ( HO )  (4)  C,H4.CH2.CH  ( NH2 )  .COOH  —  one 
of  the  earliest  known  products  of  protein  decomposition.  Tyrosine  is  formed 
from  proteins,  particularly  from  casein,  by  the  action  of  proteolytic  enzymes, 
and  during  putrefaction,  and  is  also  formed  from  them  by  boiling  with  HC1  or 
H2SO4,  or  by  fusion  with  KOH,  always  accompanied  by  leucine.  It  exists 
normally  in  the  intestine,  and  pathologically  in  the  urine.  It  has  been 
formed  synthetically,  from  phenyl-acetaldehyde,  C6H6.CH2.CHO,  by  conversion 
into  phenyl-alanine,  C6H5CH2.CH(NH2)  .COOH  and  p-amido-phenyl- a -alanine, 
C«H4(NH2)(4)  CH2.CHNH2.COOH.  It  crystal li/es  in  silky  needles,  arranged  in 
stellate  bundles,  very  sparingly  soluble  in  cold  water,  soluble  in  150  parts  of 


NITROGEN-CONTAINING   DERIVATIVES   OF  BENZENE  375 

hot  water,  *more  soluble  in  the  presence  of  acids  or  of  alkalies,  insoluble  in 
alcohol  and  in  ether.  It  unites  with  acids  and  bases  to  form  salts.  When 
heated  it  turns  brown  and  gives  off  the  odor  of  phenol;  when  heated  to  270°, 
it  is  decomposed  into  C02  and  oxyphenylethyl-amine,  C6H4(OH).CH2.CH2.NH2, 
which  sublimes. 

With  H2SO4,  and  slightly  warmed,  it  dissolves  with  a  transient  red  color; 
the  solution,  cooled,  diluted,  neutralized  with  BaC03,  and  filtered,  gives  a  violet 
color  with  FeCl3  (Piria's  reaction).  When  moistened  with  HNO3  and  slowly 
evaporated,  it  leaves  a  yellow  residue,  which  forms  a  deep  reddish-yellow  color 
with  NaOH  (Scherer's  reaction).  Heated  with  water  and  a  few  drops  of 
Millon's  reagent  it  gives  a  red  liquid,  and  forms  a  red  precipitate  (Hofmann's 
reaction).  It  gives  the  diazo  reaction. 

p-Amidophenyl-  a  -alanine—  NH2(4)C6H4.CH2.CH  (NH2)  .COOH  —  produced  by 
reduction  of  p-nitrophenyl-alanine,  is  both  a  phenyl-amido  and  an  amido-phenyl 
acid. 

Anilido  Acids  derived  from  the  monocarboxylic  acids  are  produced  by  the 
action  of  the  monochlor-acids  upon  aniline,  as  the  aliphatic  amido-acids  are 
obtained  from  ammonia.  Thus  monochloracetic  acid  and  aniline  yield  anilido- 
acetic  acid,  or  phenyl  glycocoll,  CH2C1.COOH+C8H5.NH2=C6H5.NH.CH2.- 
COOH+HC1. 

Hippuric  Acid  —  Benzoyl-amido-acetic  acid  —  Benzoyl  glycocoll 
—  C6H5.CO.NH.CH2.COOH—  is  similarly  obtained  from  monochlor- 
acetic acid  and  benzamide  : 

CH2C1.COOH+C6H5.CO.NH2=C6H5.CO.NH.CH2COOH+HC1 

It  is  also  formed  by  the  action  of  benzoyl  chloride  upon  glycocoll 
in  the  presence  of  sodium  hydroxide: 

CH2(NH2).COOH+C6H5.CO.C1=C6H5.CO.CH2.NH.COOH+HC1 

Hippuric  acid  exists  in  the  urine  of  the  herbivora  ;  and  in  human 
urine  in  the  daily  quantity  of  0.29-2.84  grams,  and  in  larger  amount 
when  benzoic  acid,  cinnamic  acid  and  other  aromatic  substances  are 
taken.  It  crystallizes  in  prisms,  colorless,  odorless,  bitter,  sparingly 
soluble  in  water,  readily  soluble  in  alcohol,  fuses  at  187°.  When 
heated  with  acids  or  alkalies  it  is  decomposed  into  benzoic  acid  and 
glycocoll.  Oxidizing  agents  convert  it  into  benzoic  acid,  benzamide 
and  carbon  dioxide.  When  heated  alone  it  gives  off  a  sublimate  of 
benzoic  acid  and  the  odor  of  hydrocyanic  acid.  Its  ferric  salt  is  in- 
soluble, and  is  formed  as  a  brown  precipitate  when  FeCl3  is  added 
to  its  solution.  Heated  with  lime  it  forms  benzene  and  ammonia. 

Anilic  Acids  are  anilido  acids  corresponding  to  the  dicarboxylic  acids. 
They  may  be  considered  as  being  formed  by  substitution  of  the  univalent  re- 
mainder of  the  acid  for  H  in  aniline,  and  therefore  as  anilides  (p.  372)  ;  or 
by  substitution  of  phenyl  for  H  in  the  NH2  group  of  the  amic  acids.  Thus 
oxanilic  acid,  C6H3.NH.CO.COOH,  corresponds  to  oxalic  acid,  COOH.COOH,  and 
to  oxamic  acid,  CONH2.COOH. 
/OTT 

Carbanilic  Acid  —  ^:^\>JHCH  —  ^e  an^c  ac^  corresponding  to  carbonic 


and  carbamic  acids,  and  isomeric  with  phenyl  urethane  (p.  314),  is  not  known  in 
the  free  state.  Its  esters,  however,  are  known  as  phenyl  urethanes.  A  great 
number  of  phenyl-urea  and  phenyl-guanidine  derivatives  are  also  known. 


376  TEXT-BOOK   OF    CHEMISTRY 

Related  to  the  amido  acids  are  the  hydroxamic  acids  and  the  anil  acids. 

Hydroxamic    Acids   are   derivable   from   the   imide    formula   of   benzamide 

(p.  373)  by  substitution  of  OH  for  H  in  the  imide  group.     Thus  benzhydrox- 

amic  acid,  C6H5.C^™,  corresponds  to  benzamide,  C.H5C.^**.  Both  H 
atoms  in  the  OH  groups  are  replaceable  by  alkyls  to  form  esters.  Amidoximes 
(p.  300)  are  derived  from  the  hydroxamic  acids  by  substitution  of  NH2  for  OH, 
e.g.,  benzenylamidoxime,  CeH5.C  \NH 

Anil  Acids  are  aniline  derivatives  of  the  ketone-carboxylic  acids,  formed 
by  the  union  of  aniline  and  the  acid,  with  elimination  of  water.  Thus  aniline 
and  pyroracemic  acid  yield  anil-pyroracemic  acid: 

C9H5.NH2-j-CH,.CO.COOH=H2O-(-C6H5.N :  C  ( CH3 )  .COOH 

DIAZO,  DIAZOAMIDO,  AND  AZO  COMPOUNDS. 

Diazo  compounds  contain  the  group  — N:N — ,  united  by  one 
bond  to  an  aromatic  group,  and  by  the  other  to  an  acid  radical. 

Diazoamido  compounds  contain  the  group  — N:N.NH — ,  united 
to  two  aromatic  groups. 

Azo  compounds  contain  the  group  — N:N — ,  united  to  two  aro- 
matic hydrocarbon  groups,  or  to  one  aromatic  and  one  aliphatic  hy- 
drocarbon group. 

Diazo  Compounds — are  derivatives  of  diazobenzene,  C6H5.N:NH, 
which  is,  however,  only  known  in  compounds  in  which  the  imide  H 
has  been  replaced  by  acidyls  or  halogens,  or  of  other  cyclic  compounds 
having  the  structure  R.NrN.X,  in  which  R  is  a  cyclic  hydrocarbon 
radical  and  X  an  acidyl  or  a  halogen.  These  diazo  compounds  are 
very  unstable,  decomposing  explosively  on  slight  elevation  of  tem- 
perature or  by  shock.  They  are  therefore  rarely  isolated  in  their  own 
form  of  crystalline  solids,  but,  on  the  other  hand,  their  instability,  or 
reactivity,  renders  their  formation  as  intermediate  products  very 
serviceable  in  the  formation  of  synthetic  products,  and  in  the  manu- 
facture of  the  "azo  dyes, "  which  include  most  of  the  so-called  "ani- 
line colors."  Their  utility  in  this  regard  depends  upon  the  facility 
with  which  the  diazo  group,  .N:NX  is  displaced  by  other  univalents, 
such  as  OH,  H,  CN,  and  halogens. 

The  diazo  compounds  are  produced  by  the  action  at  low  tempera- 
ture of  HN02  upon  the  salts  of  the  aromatic  primary  amines.  Thus 
aniline  chloride  yields  diazobenzene  chloride: 

C6H5.NH3C1+HN02=C6H5.N  :NC1+2H20 

But  if  the  temperature  is  allowed  to  rise  the  action  proceeds 
further,  with  elimination  of  N  and  formation  of  a  phenol : 

C6H5.N  :NCl+H20=C6H5.OH+N2-fHCl 

the  sum  of  the  reactions  upon  the  amine  being  then  the  same  as 
that  of  HN02  upon  the  aliphatic  primary  amines,  i.e.,  the  substitu- 
tion of  OH  for  NH2,  thus 

C0H5.NH2+HN02=C6H5.OH+N2+H20 


NITROGEN-CONTAINING   DERIVATIVES  OF  BENZENE  377 

This  method  of  formation  and  decomposition  of  the  diazo  com- 
pounds is  frequently  utilized  for  the  introduction  of  hydroxyl  into 
aromatic  molecules,  starting  either  from  the  hydrocarbon  or  inter- 
mediate forms  of  nitro  or  amido  derivatives.  The  process  is  referred 
to  as  diazotizing.  A  similar  decomposition  is  effected  by  simply 
boiling  aqueous  solutions  of  diazo  compounds : 

C6H5.N:N.HS04+H20=C6H5.OH+N2+H2S04 

The  replacement  of  the  diazo  group  by  H,  with  formation  of  the 
hydrocarbon,  is  effected  by  boiling  with  strong  alcohol,  which  is 
oxidized  to  aldehyde: 

C6H5.N:N.HS04+CH3.CH2OH=C6H6+N2+H2S04+CH3.CHO 

The  hydracids  bring  about  the  substitution  of  halogen  for  the 
diazo  group,  with  formation  of  a  monohalide: 

C6H5.N  :N.HS04+HI=C6H5I+N2+ H2S04 

A  similar  decomposition  is  effected  by  CuCl,  and  by  PtCl4  or 
PtBr4.  Diazobenzene  chloride  in  presence  of  CuS04  is  converted  by 
KCN  into  diazobenzene  cyanide,  which  then  splits  off  N  to  form 
cyanobenzene : 

C6H5.N  :N.C1+KCN=C6H8.N  :N.CN+KC1,  and 
C6H5.N  :N.CN=C6H5.CN+N2 

Notwithstanding  the  instability  of  the  attachment  of  the  diazo 
group,  the  diazo  compounds  also  enter  into  reactions  in  which  the  N 
is  not  split  off.  Thus  nascent  hydrogen  reduces  the  diazo  salts  to 
phenylhydrazine  salts  (p.  379)  : 

C6H5.N:N.S03K+H2=C6H5.HN.NH.S03K 

With  substances   containing  the   grouping — CH2.CO — the   diazo 
compounds  react  in  alkaline  solution  to  form  hydrazones  (p.  380),  in 
which,  however,  the  hydrazone  group  replaces  H2,  not  0.    Thus  with 
the  malonic  ester : 
C6H5.N  :N.C1+H2C :  ( COOC2H5)  2=C6H5.HN.N  :C :  ( COOC2H5)  2+HCl 

With  the  primary  amines,  whether  aliphatic  or  aromatic,  the  diazo 
compounds  form  diazoamido-  or  disdiazoamido  compounds  (below). 
With  the  phenols  the  diazo  salts  do  not  produce  azoxy  compounds  (p. 
378),  but  first  diazo  oxy  compounds: 

C6H5.N  :N.HS04+C6H5.OH=C6H5.N  :N.O.C6H5+H2S04, 

which    suffer    atomic    transposition    to    form    oxyazo    compounds: 
C6H5.N:N.CGH4.OH,  as  do  the  diazoamido  compounds  (below). 

Diazoamido  and  Disdiazoamido  Compounds. — The  diazoamido 
compounds,  containing  the  group  — N:N.NH —  united  to  two  aro- 
matic groups,  are  formed  by  the  action  upon  each  other  of  diazo 
salts  and  primary  or  secondary  amines  in  equal  molecular  proportion. 


378  TEXT-BOOK   OF   CHEMISTRY 

Thus  diazoamido  benzene,  C0H5.N  :N.NH.C0H5,  is  formed,  as  a  yellow, 
crystalline,  explosive  solid,  insoluble  in  water,  soluble  in  hot  alcohol, 
by  the  action  of  diazobenzene  nitrate,  or  chloride,  upon  aniline: 

C6H5.N  :NC1+NH2.C0H5=C6H5.N  :N.NH.C6H5+HC1 

The  most  notable  property  of  these  substances  is  their  transfor- 
mation, by  intramolecular  rearrangement  into  the  isomeric  p-azo- 
amido  compounds.  Thus  diazoamido  benzene  becomes  p-azo-amido 
benzene,  C6H5N:NC6H4.(NH2)  (4)  .  This  intramolecular  transposition 
takes  place  slowly  in  the  presence  of  traces  of  aniline  salts,  at  the 
ordinary  temperature. 

The  disdiazoamido  compounds,  containing  the  group  —  NrN.NH.- 
N:N  —  ,  are  formed  under  the  same  conditions  as  the  diazoamido 
compounds,  except  that  two  molecules  of  the  diazo  salts  are  taken 
for  one  of  the  amine: 

2C6H5.N  :NC1+NH2.CGH5=C6H5.N  :N.N(CCH5)  .N  :N.C6H5+2HC1 

Azo  Compounds.  —  The  azo  compounds  contain  the  same  group, 
—  N:N  —  ,  as  the  diazo  compounds,  but  they  differ  from  the  latter  in 
that  the  two  valences  are  both  satisfied  by  hydrocarbon  groups  j 
either  both  aromatic,  as  in  azobenzene,  C8H5.N  :N.C6H5,  or  one 
aromatic  and  one  aliphatic,  as  in  benzene  azo-methane,  C6H5.N:N.- 
CH3.  They  are  '  '  mixed,  ""  symmetric,  '  '  and  '  *  unsymmetric,  '  '  accord- 
ing as  they  contain  an  aromatic  and  an  aliphatic  group,  or  two  like 
aromatic  groups,  or  two  unlike  aromatic  groups.  In  designating  the 
orientation  of  substituted  groups  the  —  N:N  —  attachments  are  con- 
sidered as  occupying  the  (1)  position  in  both  hydrocarbon  groups, 
and  the  positions  of  substitution  in  one  ring  are  indicated  by  2,  3, 
etc.,  and  those  in  the  other  by  2',  3',  etc. 

The  azo  compounds  are  formed:  (1)  By  moderate  reduction  of 
nitro-aromatic  compounds  in  alkaline  solution.  The  reaction  takes 
place  in  two  stages,  an  azoxy  compound  being  first  formed  and  then 
further  reduced.  Thus  nitro-benzene  forms,  first  azoxybenzene,  then 


azobenzene  : 

.N02 


2C6H5.N02+3H2=C6H5.N^1N.CGH5+3H20,  and  then 
N.C6H5+H2=C6H5.N  :N.C6H5+H20 


The  reduction  readily  progresses  further,  and  always  does  so  in 
acid  solutions,  with  formation,  first  of  a  hydrazo  product  (p.  379), 
and  finally  an  amido  derivative  (pp.  371,  373).  Thus  azobenzene 
forms,  first,  hydrazobenzene,  or  symmetrical  diphenyl  hydrazine,  and 
then  aniline  : 

C6H5.N  :N.C0H5+H2=C0H5.NH.NH.C6H5,  and 
C6H5.NH.NH.C6H5+H2=2C0H5.NH2 

(2)  By  reduction  of  the  azoxy  compounds.  (3)  The  amido  de- 
rivatives of  the  azo  hydrocarbons  are  technically  manufactured  by 


NITROGEN-CONTAINING   DERIVATIVES   OF  BENZENE  379 

molecular*  rearrangement  of  the  diazoamido  compounds  (p.  378),  or 
(4)  by  acting  upon  the  tertiary  anilines,  or  upon  the  m-diamines, 
with  diazo  salts. 

The  azo  compounds  are  much  more  stable  than  the  diazo  com- 
pounds. The  hydrocarbons,  such  as  azobenzene,  C6H5.N:N.C6H5, 
are  highly  colored  crystalline  solids,  which  are  not  basic,  and  do  not 
act  as  dyes.  They  are  sparingly  soluble  in  water,  readily  soluble  in 
alcohol  and  in  ether.  Their  most  important  derivatives  are  the 
amido-azo  compounds,  which  are  highly  colored  and  strongly  basic, 
crystalline  solids,  whose  solutions  have,  however,  no  dyeing  power. 
But  they  combine  readily  with  salt-forming  groups,  notably  to  form 
sulphonic  acids,  which  constitute  many  of  the  most  extensively  used 
"aniline  dyes." 

p-Amido-azobenzene  —  C6H5.N  :N.(C6H4)  (NH2)  (4)  — prepared  by 
the  methods  given  above,  is  the  starting  point  in  the  manufacture  of 
several  yellow,  orange,  and  brown  l '  diazo  dyes, ' '  and  of  the  * '  inuline 
dyes."  It  forms  yellow  needles,  fusing  at  123°. 

HYDRAZINE  COMPOUNDS. 

The  aromatic  hydrazines  are  derived  from  diamide,  H2N.NH2, 
by  substitution  of  hydrocarbon  or  other  aromatic  radicals  for  one 
or  more  of  the  hydrogen  atoms. 

Hydrazo-benzene  —  sym.  Diphenyl-hydrazine  —  C6H5.NH.NH.- 
C6H5 — is  obtained  by  moderate  reduction,  as  with  zinc  dust  or  sodium 
amalgam,  of  azobenzene: 

CaH5.N:N.C6H5+H2=C6H5.NHjra.C6H5 

It  forms  colorless  crystals,  having  the  oclor  of  camphor,  fusible 
at  132°,  insoluble  in  water,  soluble  in  alcohol  and  in  ether.  It  readily 
oxidizes  to  azobenzene.  Strong  reducing  agents  break  it  up  into  two 
molecules  of  aniline.  It  is  not  basic;  but,  when  treated  with  strong 
acids,  it  suffers  molecular  rearrangement,  with  formation  of  ben- 
zidine.  or  p(2rdiamido-diphenyl,  NH2(4).C6H4.C6H4.NH2(4). 

The  unsymmetrical  hydrazines  resemble  each  other  in  their  prop- 
erties and  methods  of  formation,  but  differ  from  the  symmetrical 
compounds,  notably  in  that,  containing  the  — NH.NH2  group,  they 
are  monacid  bases,  forming  salts  corresponding  to  those  of  ammonia. 

Phenylhydrazine — C6H5.NH.NH2 — is  formed  by  reduction  of  the 
diazo  salts,  of  the  diazo-amido  compounds,  or  of  the  nitroso-amines. 
Thus  stannous  chloride  and  diazobenzene  chloride  yield  phenylhydra- 
zine  hydrochloride : 

C6H5N:NGl+2SnCl2+4HCl=C6H5.NH.NH3Cl+2SnCl4 

Zinc  dust  and  acetic  acid  decompose  diazoamido-benzene  into 
phenylhydrazine  and  aniline : 

C6H5.N:N.NH.C6H5+2H2=C6H5.NH.NH2+NH2.C6H5 


380  TEXT-BOOK   OF   CHEMISTRY 

Phenylhydrazine  is  a  yellow  oil,  which  crystallizes  at  23°,  and 
boils  at  242°  with  partial  decomposition,  or  at  120°,  without  decom- 
position, under  12mm.  pressure.  It  reduces  Fehling's  solution,  or 
when  boiled  with  CuS04  it  liberates  nitrogen  and  forms  benzene. 
Sodium  displaces  the  imide  H  to  form  a  sodium  phenylhydrazine : 
C6H5.NaN.NH2.  The  alkyl  halides  cause  substitution  of  alkyls  for 
both  amide  and  imide  H,  forming  a  and  ft  phenylalkyl  hydrazines. 
One  of  the  latter,  ft  methyl-phenylhydrazine,  C6H5.NH.NH.CH3, 
is  an  intermediate  product  in  the  formation  of  antipyrine  from 
phenylhydrazine.  Heated  to  200°  with  fuming  HC1,  phenyl- 
hydrazine is  converted  into  p-phenylene-diamine :  C6H5.NH.NH2=: 
NH2.C6H4.NH2. 

Phenyl-hydrazones  and  Osazones. — A  most  important  action  of 
phenylhydrazine  is  that  with  aldehydes  and  ketones,  and  with  aldo- 
and  keto-alcohols,  and  aldehyde  and  ketone  acids  and  their  esters, 
in  which  the  bivalent  remainder  =N.NH.C6H5  takes  the  place  of 
oxygen  in  the  aldehyde  or  ketone  group,  with  the  formation  of 
phenyl-hydrazones  and  osazones,  in  much  the  same  manner  as  the 
aldoximes  and  ketoximes  are  formed  from  the  aldehydes  and  ketones. 
The  formation  of  these  derivatives  is  utilized  to  identify  the  alde- 
hydes and  ketones  and,  notably,  the  aldoses  and  ketoses  (p.  236,  also 
"phenylhydrazine  reaction"). 

The  phenyl-hydrazones  and  osazones  are  formed  by  a  variety  of 
methods,  usually  by  heating  the  aldehyde  or  ketone  compound  with 
phenylhydrazine  hydrochloride  in  presence  of  sodium  acetate.  In  the 
formation  of  the  aldehydrazones  and  ketohydrazones  the  reaction 
takes  place  with  elimination  of  water  according  to  the  equations: 

CH3.CH2.CHO+H2N.NH.C6H5r=CH3.CH2CH:N.NH.C6H5+H,0, 
and    CH3.CO.CH3+H2N.NH.C6H5=:CH3.C :(N.NH.C6H5).CH3+H20 

In  the  formation  of  the  osazones  of  the  aldoses  and  ketoses  two 
molecules  of  phenylhydrazine  react  with  one  of  the  sugar,  with  elimi- 
nation of  water.  In  the  first  stage  of  the  reaction  a  hydrazone  is 
formed  as  with  the  aldehydes  and  ketones.  Thus  with  glucose  and 
fructose  respectively  (pp.  240,  241) : 

CHO  CH:N.NH.CflH6 

(CHOH)4-fH2N.NH.C4(H5  =  (CHOH)4  -fH2O,  and 

CH,OH  CH,OH 

CH,OH  CH2OH 

CO  C:N.NH.C6H5 

( CHOH )  ,+H2N.NH.C6H1,  =  ( CHOH ) ,  +  HaO ; 

CH,OH  CHZOH 


HYDROCARBONS  381 

The  CHOH  or  CH2OH  group  vicinal  to  the  first  substitution  then 
becomes  oxidized  to  CO  or  CHO,  and  a  second  =N.NH.C6H5  group 
is  substituted  for  the  0  to  form  the  osazone : 

CH:N.NH.C6H5  CH:N.NH.C6H5 

CO  C:N.NH.C8H5 

(CHOH) 3  -fH2N.NH.C9H5  =  (CHOH),  +H20,  and 

CH2OH  CH2OH 

CHO  CH:N.NH.C6H, 

C :  N.NH.C6H5  C :  N.NH.C9H6 

(  AnOH  )  3  +H2N.NH.CaH6  =  ( feOH )  s  +H20, 

CH2OH  CH2OH 

A  comparison  of  the  above  formulae  will  indicate  why  it  is  that 
glucose  and  fructose  yield  one  and  the  same  osazone,  called  glucosa- 
zone. 

The  phenyl-hydrazones  are  also  utilized  in  the  formation  of  con- 
densed heterocyclic  compounds.  Thus  acetone  phenyl  hydrazone, 

CH3.C  :N.NH.C6H5  CH3.C.NH\ 

is  converted  into  a  methyl  indole  (p.  415), 

CH3  CH    / 

C6H4,  by  loss  of  NH3. 

Acid  Derivatives  of  Phenylhydrazine. — A  great  number  of  compounds  are 
known,  formed  by  the  substitution  of  acid  radicals  for  the  amide  or  imide 
hydrogen  of  phenylhydrazine.  These  compounds  bear  the  same  relation  to 
phenylhydrazine  that  the  anilides  bear  to  aniline,  and  some  of  them  have  been 
used  as  antipyretics,  e.  g.,  /3  acetophenyl-hydrazide — Hydracetine — C6H8.- 
NH.NH.CO.CH3 — formed  as  a  white,  crystalline,  tasteless,  and  odorless  powder, 
sparingly  soluble  in  water,  by  the  action  of  acetyl  chloride  or  of  acetic  an- 
hydride upon  phenylhydrazine.  It  is  the  active  ingredient  of  an  antipyretic 
called  pyrodine. 

B.  HYDROAROMATIC  COMPOUNDS  WITH  A  SINGLE 

NUCLEUS. 

The  hydroaromatic  compounds  may  be  considered  as  derived  from 
the  benzenic  by  rupture  of  one  or  more  of  the  double  linkages  of  the 
benzene  ring  (p.  336),  by  which  the  valence  of  the  nucleus  is 
changed  from  six  to  eight,  ten  or  twelve. 

HYDROCARBONS. 

Hexahydrobenzenes— Cyclohexanes— Naphthenes—  These  compounds,   of 

which  hexahydrobenzene,  H2C\cH2  CH22/CHz'  is  the  simPlest>  and  the  Parent 
substance  of  the  hydroaromatic  compounds,  exist  in  Russian  petroleum,  in  coal 
tar,  and  in  "rosin-oils."  They  are  isomeric  with  the  defines,  from  which  they 


382  TEXT-BOOK   OF    CHEMISTRY 

may  be  distinguished  by  the  fact  that  they  do  not  combine  with  bromine. 
With  chlorine  they  form  mono-chlor  substitution  products  which  behave  like 
alkyl  chlorides. 

Terpenes.  —  Most  of  the  volatile,  or  essential  oils,  or  essences,  obtained  by 
distillation  of  various  plants  with  steam,  consist  of  hydrocarbons  having  the 
formula  C10Hia,  and  most  of  the  camphors  and  resins  are  alcoholic  or  ketonic 
derivatives  of  these  hydrocarbons.  A  few  of  the  essential  oils,  having  the 
formula  C5H8,  are  known  as  hemiterpenes,  or  define  terpenes,  and  are  un- 
saturated  aliphatic  compounds.  Some  of  the  aromatic  terpenes  also  are  poly- 
meres,  having  the  formulae  x  (  C5H8  )  .  Although  the  constitution  of  the  aromatic 
terpenes  is  not  completely  established,  they  are  hydro-aromatic  hydrocarbons  of 
which  the  camphors  are  alcohols  or  ketones. 

Turpentine  is  a  yellowish-white,  semi-solid  substance,  having  a  balsamic 
odor,  which  exudes  from  incisions  in  the  bark  of  Pinus  palustris,  P.  tceda,  and 
other  Coniferce,  and  which  may  be  taken  as  the  type  of  a  number  of  other 
similar  products.  These  substances,  when  distilled  with  steam,  yield  two 
products,  one  a  solid,  yellow  or  brown  residue,  a  stearoptene,  such  as  rosin  or 
colophany;  the  other  a  volatile,  oily  liquid,  an  eleoptene,  such  as  oil,  or 
essence,  of  turpentine.  Oil  of  turpentine  is  insoluble  in  water,  mixes  with 
alcohol  and  with  ether,  and  dissolves  phosphorus,  sulphur  and  caoutchouc. 
When  exposed  to  the  air  it  is  oxidized  to  gummy,  aldehydal  products,  which 
finally  harden,  hence  its  use  as  a  drier  in  the  manufacture  of  paints  and  var- 
nishes. On  contact  with  HNO3,  its  oxidation  is  so  violent  as  to  cause  ignition. 

Hydroterpenes  are  naphthenes    (p.  381)   obtained  by  decomposition  of  cer- 

tain natural  alcohol-camphors.    Thus  hexahydrocymene,  H3C.CH  \CH2C:H2/ 

CH.CH/™',  is  derived  from  menthol    (p.  383). 
\U±13 

HYDROAROMATIC  ALCOHOLS. 

The  hydroaromatic  alcohols  are,  for  the  most  part,  "ring  alcohols,"  and 
contain  either  CHOH  or  COH,  as  a  part  of  the  ring,  although  in  some,  as  in 
some  of  the  terpan  alcohols,  the  alcoholic  group,  which  may  then  also  be 
CH2OH,  is  contained  in  the  lateral  chain.  These  alcohols  may  be  obtained  by 
reduction  of  the  corresponding  ketones,  or  of  other  aromatic  or  hydroaromatic 
compounds.  They  are  produced  by  the  action  of  organic  magnesium  compounds 
by  reactions  similar  to  those  by  which  aliphatic  alcohols  are  formed  (p.  212). 
Magnesium  cyclohexane  chlorides  are  obtained  by  the  action  of  magnesium 
upon  cyclohexane  chlorides: 


and  these  in  turn  react  with  aldehydes  and  ketones  to  produce  crystalline 
compounds  from  which  the  alcohols  are  produced  by  hydrolysis.  Thus  cyclo- 
hexyl  carbinol  is  produced  from  hexahydrobenzene  and  trioxymethylene  : 

C6Hn.Mg.Cl-fH.CHO=:CaHn.CH2O.Mg.Cl    and 
C6Hu.CH2O.Mg.Cl-fH2O=C6Hn.CH2OH+HO.Mg.Cl. 

Several  of  them,  such  as  quercite,  inosite  and  some  of  the  camphors,  are 
natural  products. 

Quercite—  H2C  \CHOHiCHOH  /  CH°H—  a  pentatomic  alcohol,  obtained 
from  acorns.  It  is  a  sugar-like  substance,  but  is  not  affected  by  alkalies,  does 
not  ferment,  and  does  not  reduce  Fehling's  solution.  F.  p.  235°;  [a]D=  -f24.16°. 

Inosite—  CaH6  (  OH  )  fl—  CHOH  \  CHOH  CHOH/  CHOH—  metameric,  though 
not  rrlat-d,  to  the  glucoses,  is  a  hexatomic  alcohol,  which  exists  in  three  optical 
modifications.  The  inactive  modification  exists  in  the  liquid  of  muscular  tissue, 


HYDROAROMATIC   KETONES   AND   ACIDS  383 

in  the  lungs,  kidneys,  liver,  spleen,  brain  and  blood;  in  traces  in  normal  urine, 
and  increased  in  Bright's  disease,  in  diabetes,  and  after  the  use  of  drastics  in 
uremia  ;  in  the  contents  of  hydatid  cysts  ;  in  beans  and  peas,  and  in  certain 
other  seeds  and  leaves.  It  crystallizes  in  needles,  usually  arranged  in  cauli- 
flower-like masses,  has  a  sweet  taste,  is  readily  soluble  in  water,  sparingly 
soluble  in  alcohol,  insoluble  in  absolute  alcohol  and  in  ether.  It  does  not  fer- 
ment, is  not  colored  by  alkalies,  and  does  not  reduce  Fehling's  solution.  When 
heated  to  170°  with  HI,  it  is  decomposed  into  phenol,  diiodophenol  and  benzene. 
When  treated  with  HN03  evaporated  to  near  dryness,  the  residue  moistened  with 
NH4OH  and  CaCl2,  and  again  evaporated,  a  rose-red  residue  is  left  (Scherer's 
reaction).  Mercuric  nitrate  produces  in  solutions  of  inosite  a  yellow  precipitate, 
which,  on  cautious  heating,  turns  red.  The  color  disappears  on  cooling  and 
reappears  on  heating  (Gallois'  reaction). 


Menthol—  Oxyhexahydrocymene  —  H,C.CH  GH.CH 

—  is  a  monacid  menthan  alcohol.  It  is  the  chief  constituent  of  oil  of  peppermint. 
It  crystallizes  in  prisms,  fusible  at  42°,  sparingly  soluble  in  water,  readily 
soluble  in  alcohol,  ether  and  carbon  bisulphide,  and  in  acids.  Corresponding 
to  it  are  a  series  of  menthyl  esters. 

Terpins.  —  There  are  two  diacid  menthan  alcohols,  in  which  the  hydroxyls 
occupy  the  1.8  positions.  The  formula  of  cis-terpin,  the  parent  substance  of 

H3C\    /CH2.CH2\ 

terpin  hydrate  and  of  cineol,  is  now  considered  as  being  C  C- 

HO/    \CH2.CH2/ 

/TT  /  OTT 

(  C=(CH  )  >while  in  trans-terpin  the  positions  of  the  CH3  and  OH  attached  to 
C  (  1  )  are  reversed.  Cis-terpin  is  obtained  by  dehydration  of  terpin  hydrate, 
and  also  from  [d-)-l]-limonene  dihydrochloride.  It  is  crystalline,  fuses  at  104°, 
and  boils  at  258°.  It  absorbs  water  eagerly  to  form  terpin  hydrate.  Gaseous 
HC1,  or  PC13,  converts  it  into  [d-fl]-limonene  hydrochloride. 

Terpin  Hydrate  —  Ci0H18  (  OH  )  2-|-H2O  —  is  formed  when  oil  of  turpentine  re- 
mains long  in  contact  with  water,  more  rapidly  in  presence  of  alcohol  and 
dilute  HN03;  also,  similarly,  from  pinene  and  from  limonene.  It  forms 
rhombic  crystals,  fusible  tit  117°,  with  loss  of  H20  and  conversion,  slowly, 
into  terpin.  It  is  easily  soluble  in  alcohol,  sparingly  soluble  in  water,  chloro- 
form and  ether.  It  is  used  as  an  expectorant. 

Cineol  —  Eucalyptol  —  C10H16(OH)2  —  another  diacid  menthan  alcohol  is  ob- 
tained from  the  leaves  of  Eucalyptus  globulus,  and  also  exists  in  wormseed  oil 
(Oleum  cince)  and  in  other  volatile  oils.  It  is  a  colorless  oil,  having  a  camphor- 
like  odor;  sp.  gr.  0.93  at  15°;  b.  p.  176°;  nD  ==  1.4559;  soluble  in  alcohol, 
sparingly  soluble  in  water.  Dry  HC1  gas  passed  through  its  petroleum  ether 
solution  separates  white  scales  of  eucalypteol,  C10H16.2HC1,  which  is  decomposed 
by  water  with  regeneration  of  cineol. 

Borneol  —  Camphol  —  Borneo  Camphor  —  C10H180  —  a  monacid  alcohol,  is 
the  best  known  of  the  camphan  alcohols.  It  exists  in  three  optical  modifica- 
tions; the  d-borneol  being  the  one  usually  met  with,  and  obtained  from 
Dryobalanops  camphora.  The  d-  and  1-modifications  are  both  formed  by  hydro- 
genation  of  laurel  camphor.  It  forms  small,  friable  crystals;  has  an  odor  re- 
calling those  of  laurel  camphor  and  of  pepper,  and  a  hot  taste;  is  insoluble  in 
water,  readily  soluble  in  alcohol,  ether,  and  acetic  acid;  fuses  at  203°;  boils 
at  212°.  It  is  oxidized  to  laurel  camphor  by  HN03.  Heated  with  KHS04, 
it  is  decomposed  into  camphene  and  H20. 

HYDROAROMATIC  KETONES  AND  ACIDS. 

The  hydroaromatic  ketones  are  "  ring  ketones,"  the  CO  group  forming  a 
part  of  the  ring.  They  are  formed:  (1)  by  reduction  of  the  corresponding 


384  TEXT-BOOK   OF    CHEMISTRY 

aromatic   phenols;     (2)    by   oxidation    of   the   secondary   ring-alcohols:     (3)    by 
condensation  of  the  esters  of  the  aliphatic  ketone  acids,  or  of  the  ketones. 

d-Camphor — Common  camphor — Laurel  camphor — Japan  cam- 
phor— C10H160 — is  the  most  important  of  the  hydroaromatic  ketones. 
It  is  obtained  from  the  camphor  tree  (Laurus  camphora),  and  is 
formed  artificially  by  oxidation  of  borneol  or  of  camphene.  It  forms 
translucent,  friable  crystals;  hot  and  bitter  in  taste,  aromatic;  spar- 
ingly soluble  in  water,  quite  soluble  in  acetic  acid,  methylic  and 
ethylic  alcohols,  and  the  oils;  f.  p.  175°;  b.  p.  204°;  sp.  gr.  0.985; 
sublimes  at  all  temperatures;  [a]D=  -(-44.22. 

It  ignites  readily,  and  burns  with  a  luminous  flame.  Cold  HN03 
dissolves  it,  and  H20  precipitates  it  unchanged  from  the  solution. 
Hot  HN03,  or  potassium  permanganate,  oxidizes  it  to  d-camphoric 
acid.  Distilled  with  P205  it  yields  cymene,  C10H14.  Reducing  agents 
convert  it  into  borneol.  Heated  with  iodine,  it  is  converted  into  car- 
vacrol.  Bromine  unites  with  it  to  form  ruby-red  crystals  of  an  un- 
stable compound,  C10H14OBr2,  which,  when  heated,  fuse  and  give  off 
HBr,  leaving  an  amber-colored  residue,  which,  on  recrystallization 
from  boiling  alcohol,  leaves  long,  hard,  rectangular  crystals  of 
monobromo-camphor,  C10H15OBr;  f.  -p.  76°;  soluble  in  alcohol  and 
in  ether. 

1-Camphor  is  obtained  from  the  oil  of  Matricaria  postlanium; 
[a]D  =  — 44.22°.  [d+1]  -Camphor  exists  in  the  essential  oils  of 
rosemary,  sage,  lavender  and  origanum,  or  is  formed  by  mixing  d- 
and  1-  camphors,  or  by  oxidation  of  [d+1] -borneol,  or  of  [d+1]- 
camphene.  F.  p.  179°. 

Hydroaromatic  Carboxylic  Acids.— A  great  number  of  these  acids  are 
known,  some  pure  acids,  others  oxy-  or  ketonic  acids,  containing  from  one  to 
six  carboxyl  groups,  and  hexahydro-,  tetrahydro-  and  dihydro-.  The  most 
important  are: 

Quinic  Acid  —  Hexahydro-tetraoxybenzoic  Acid  —  C6H7  ( OH )  4COOH  - 
which  exists,  combined  with  the  alkaloids,  in  cinchona  barks,  also  in  coffee  beans 
and  in  other  plants.  It  forms  hard,  transparent  prisms,  soluble  in  water  and 
in  alcohol;  fuses  at  160°;  laevogyrous.  On  distillation,  it  yields  phenol,  hydro- 
quinol,  benzoic  acid  and  salicylic  aldehyde.  Hydriodic  acid  reduces  it  to  benzoic 
acid. 

Terebic  Acid— C7H1004— f.  p.  175°;  and  Terpenylic  Acid— C8H1204— f.  p. 
90°,  are  oxidation  products  of  oil  of  turpentine,  obtained,  the  former  with 
HNOj,  the  latter  with  chromic  acid  mixture. 

Camphoric  Acids— ChH14 ( COOH ) 2—  The  d-,  1-,  and  [d-f  11 -acids  are  known. 
d-Camphoric  acid  is  produced  by  oxidizing  common  d-camphor  by  heating  with 
HNO8.  It  forms  colorless,  odorless  needles,  soluble  in  alcohol,  ether  and  boiling 
water;  f.  p.  187°;  [a]D  =-f49.7°.  By  further  oxidation  it  yields  camphoronic 
acid,  or  trimethyl-tricarballylic  acid. 

Resins — are  generally  the  products  of  oxidation  of  the  hydro- 
carbons allied  to  pinene;  are  amorphous  (rarely  crystalline)  ;  insol- 


COMPOUNDS   WITH   CONDENSED   NUCLEI  385 

uble  in  water ;  soluble  in  alcohol,  ether,  and  essences.    Many  of  them 
contain^  acids. 

They  may  be  divided  into  several  groups,  according  to  the  nature 
of  their  constituents:  (1)  Balsams,  which  are  usually  soft  or  liquid, 
and  are  distinguished  by  containing  free  cinnamic  or  benzoic  acid, 
e.g.,  benzoin,  liquidambar,  Peru  balsam,  styrax,  balsam  tolu;  (2) 
oleo-resins  consist  of  a  true  resin  mixed  with  an  oil,  e.g.,  Burgundy 
and  Canada  pitch,  Mecca  balsam,  and  the  resins  of  capsicum,  copaiba, 
cubebs,  elemi,  lupulin;  (3)  gum-resins,  mixtures  of  true  resins  and 
gums,  e.g.,  aloes,  ammoniac,  asafetida,  eupJiorbium,  galbanum,  guaiac, 
myrrh,  olibanum,  scammony ;  (4)  true  resins,  hard  substances  con- 
taining neither  essences,  gums  nor  aromatic  acids,  e.g.,  resin,  copal, 
dammar,  jalap,  lac,  sandarac;  (5)  fossil  resins,  e.g.,  amber,  asphalt, 
ozocerite. 

C.  COMPOUNDS  WITH  CONDENSED  NUCLEI. 

These  compounds  contain  two  or  more  benzene  rings,  or  one  or 
more  benzene  rings  and  a  pentacarbocyclic  ring,  fused  together  in 
such  manner  that  the  adjacent  rings  have  two  carbon  atoms  in  com- 
mon. The  parent  hydrocarbons  of  these  compounds  are:  indene, 
fluorene,  naphthalene,  anthracene,  phenanthrene,  chrysene,  and 
picene : 


H 

H                  H 

H        H 

C 

C                   C 

C          C 

//\ 

//\            X\\ 

f/\    X\\ 

HC         C  CH 

HC        C  C         CH 

HC        C 

CH 

H(i        «        ^H 

H(l         [1        {j        <IH 

nfc      c! 

in 

\\X       \/ 

\\X   \X   \// 

\\x  \// 

C          C 

C         C         C 

c      c 

H          Ha 

H        H2      H 

H        H 

Indene. 

Fluorene. 

Naphthalene. 

H         H        H                               H   H 

H   H 

C 

C        C                               C=C 

C=C 

//\    / 

\   X\\                       X         \ 

X          \ 

HC        C 

C        CH              HC 

C—  C                 CH 

H(i  y 

C        CH                        C—  C 

C—  C 

\\  X   \ 

/    \//                             H       \ 

X       H 

c      c      c 

C=C 

H        H        H 

H  H 

Anthracene.                                                        Phenanthrene. 

The  derivatives  of  these  hydrocarbons  are  similar  in  their  general 
properties  to  the  benzene  derivatives,  with  some  differences  in  orien- 
tation. Chrysene,  C18H12,  and  picene,  C22H14,  are  naphthalene-phen- 
anthrenes.  Most  of  these  hydrocarbons  form  crystalline  addition 
products  with  picric  acid. 


386  TEXT-BOOK   OF    CHEMISTRY 


CONDENSED  HYDROCARBONS. 

These  hydrocarbons  accompany  benzene  in  coal-tar.  Naphtha- 
lene and  anthracene  are  obtained  from  this  source  industrially. 

Naphthalene — C10H8 — is  obtained  commercially  from  the  fraction 
of  coal-tar  distillation  passing  between  180°  and  300°.  It  crystallizes 
in  shining  plates ;  f .  p.  79  ° ;  b.  p.  218  ° ;  volatile  at  all  temperatures, 
giving  off  a  peculiar,  tarry  odor  (white  tar,  moth-balls)  ;  sparingly 
soluble  in  cold  alcohol,  readily  soluble  in  hot  alcohol,  ether  and 
benzene.  It  is  used  in  the  arts  in  the  preparation  of  phthalic  acid 
and  its  derivatives,  of  the  naphthols,  etc.,  and  of  a  great  number  of 
naphthalene  dyes,  for  the  carburation  of  water-gas,  and  against 
moths.  Its  picric  acid  compound  fuses  at  149°. 

Naphthalene  is  undoubtedly  formed  in  the  distillation  of  coal  by 
condensation  of  lower  hydrocarbons  under  the  influence  of  heat,  a 
formation  which  may  be  imitated  by  conducting  a  mixture  of  benzene 
vapor  with  acetylene,  or  with  ethylene,  through  a  tube  heated  to 
redness.  Naphthalene  derivatives  are  also  formed  by  condensa- 
tion of  several  monobenzenic  derivatives  with  unsaturated  lateral 
chains.  Thus  a  naphthol  is  produced  from  phenyl-isocrotonic  acid: 

/CH  -  CH  /CH    =    CH 

C6H5  |      =C6H4  I     +H20 ;  and  naphthalene  itself  is 

5  \HOOC.CH2  \C(OH):CH 

formed   when   phenylbutylene   vapor   is   passed   over   heated   lime: 

/CH=CH 
C6H5.CH2.CH2.CH:CH2=C6H4  I     +2H2. 

\CH=CH 

Hydronaphthalenes  and  their  substitution  products  are  derived 
from  naphthalene  by  rupture  of  one  or  more  of  the  double  bonds, 
in  the  same  manner  as  the  hydroaromatic  compounds  are  derived 
from  benzene. 

Anthracene — C14H10 — is  obtained  commercially  from  the  "green 
oil"  of  coal-tar,  distilling  above  270°;  and  is  used  in  the  manufac- 
ture of  alizarin  dyes  (artificial  madder).  It  is  formed  from  benzene 
and  acetylene,  or  methylene  bromide,  in  presence  of  A1C13.  It  crys- 
tallizes in  colorless  plates,  having  a  fine  blue  fluorescence ;  f .  p.  213  ° ; 
b.  p.  351°;  sparingly  soluble  in  benzene  and  in  carbon  bisulphide, 
which  are  its  best  solvents.  Oxidizing  agents  convert  it  into  anthra- 
quinone.  Its  picric  acid  compound  forms  red  needles,  f.  p.  138°. 

PHENOLS,  QUINONES. 

The  phenols,  particularly  those  of  naphthalene,  the  oxynaph- 
thalenes,  or  naphthols,  are  the  most  important  of  those  compounds. 
The  naphthols  exist  in  coal-tar,  and  are  also  manufactured  syntheti- 
cally by  the  methods  indicated  below.  They  readily  form  ethers,  and 
with  ammonia  they  produce  the  corresponding  naphthylamines.  Both 
naphthols  are  used  medicinally  as  antiseptics. 


PHENOLS,    QUINONES  387 

ar-Napbthol  —  C10H7.(OH)a — is  obtained  by  heating  phenyl 
isocrotonic  acid ;  also  by  boiling  an  aqueous  solution  of  diazonaphtha- 
lene  nitrate  with  nitrous  acid,  or  by  fusing  a  -naphthalene-sulphonic 
acid  with  KOH. 

It  crystallizes  in  colorless  prisms;  f.  p.  95°;  b.  p.  280°;  nearly 
insoluble  in  water,  soluble  in  alcohol  and  in  ether ;  is  easily  volatile, 
and  has  the  odor  of  phenol.  It  gives  a  transient  violet  color  with 
FeCl3  and  a  hypochlorite.  With  nitrous  acid  it  forms,  2,  i  and  4,  i 
nitroso-naphthols.  Potassium  chlorate  and  hydrochloric  acid  oxidize 
it  to  dichloro-naphthaquinone.  Nascent  hydrogen  (sodium  and 
alcohol)  reduce  it  to  ar-tetrahydronaphthol  (below).  Its  acetate 
fuses  at  46°. 

/? -Naphthol — C10H7(OH)/? — is  prepared  industrially  by  fusion 
of  sodium  /?-naphthalene-sulphonates  with  NaOH,  for  use  in  the 
manufacture  of  a  number  of  dyes,  among  which  are  Campobello 
yellow  and  the  tropeolins.  It  crystallizes  in  colorless,  silky  plates, 
which  turn  dark  in  daylight;  has  a  faint  phenol-like  odor,  and  a 
sharp,  burning  taste;  f.  p.  123°;  b.  p.  286°;  sparingly  soluble  in 
water,  readily  soluble  in  alcohol  and  in  ether.  It  gives  a  greenish 
color  with  FeCl3.  Its  acetate  fuses  at  70°. 

Substituted  Naphthols. — Both  naphthols  form  a  great  number  of  deriva- 
tives by  substitution  of  other  groups  for  hydrogen  atoms.  Many  of  these  are 
important  dyes.  Thus  Marthas  yellow  is  the  Na  salt  of  2,  4-dinitro-a  -naphthol, 
a  poisonous  pigment  sometimes  used  to  color  butter  and  confectionery. 
Naphthol  yellow  is  the  dipotassium  salt  of  dinitro-a-naphthol-8-sulphonic 
acid.  The  naphthols  combine  easily  with  the  diazo-  and  azo-compounds  to 
form  a  number  of  azo-naphthol  derivatives,  several  of  which  are  important 
dyes,  as  the  naphthol  oranges  and  Bieberich  scarlet.  A  great  variety  of 
naphthol-sulphonic  acids  have  also  been  prepared  for  use  in  the  color  industry, 
as  in  the  preparation  of  the  various  ponceau  and  Bordeaux  dyes.  These  sul- 
phonic  acids,  being  basic  by  their  OH  group  and  acid  by  the  HS03  group,  form 
lactone-like  compounds,  which  are  called  sultones. 

Tetrahydronaphthols  are  formed  by  the  introduction  of  four  H  atoms  into 
one  of  the  benzene  rings,  by  the  action  of  nascent  hydrogen  upon  the  naphthols. 
If  the  hydrogenation  occur  in  the  ring  containing  the  OH,  one  product  is 
obtained,  designated  by  the  prefix  ac-,  whereas  if  it  occur  in  the  other  ring  a 
different  substance  is  produced,  designated  by  the  prefex  ar-. 

Quinones. — Naphthalene,  anthracene  and  phenanthrene  readily  yield 
quinones,  some  of  which  are  technically  prepared  by  oxidizing  the  hydrocarbons 
in  acetic  acid  solution  by  chromic  acid;  or  from  the  dioxy-  or  diamido-com- 
pounds. 

Naphthoquinones. — Oxidation  of  naphthalene  produces  a  naphthoquinone, 
C10Ha:O2(1  4),  which  crystallizes  in  yellow  needles,  fusible  at  125°.  The  a- ft 
quinone,  C10H6 : 02  (1  2) ,  is  formed  by  oxidation  of  /3  amido-  a  -naphthol,  and 
crystallizes  in  red  needles,  fusible  at  115°.  Both  naphthoquinones  form  oximes 
and  hydrazones,  some  of  which  are  used  in  the  color  industry. 

Anthraquinone — Diphenylene  Diketone — C6H4  ( CO )  2 :  C6H4 — is  commer- 
cially manufactured  by  oxidation  of  anthracene.  It  forms  yellow  needles;  f.  p. 
285°;  b.  p.  382°.  It  forms  an  oxime  with  hydroxylamine,  and  sulphonic  acids 
with  H2S04,  as  well  as  chlorine,  bromine  and  oxy-  derivatives. 


388  TEXT-BOOK  OF   CHEMISTRY 

Alizarin  — i,  2-Dioxyanthraquinone  —  C«H4:  (CO)2:C6H.:  (OH)2 —  is  pre- 
pared industrially  by  the  action  of  fused  NaOH  upon  anthraquinone-monosul- 
phonic  acid,  and  is  also  formed  by  fusion  of  several  other  anthraquinone  deriva- 
tives with  caustic  alkalies.  It  is  the  coloring  principle  of  madder  (Rubin 
tinctoria),  and  the  artificial  product  has  now  completely  displaced  madder  in 
dyeing. 

Purpurin — i,  2,  4-Trioxyanthraquinone — C8H4 :  ( CO )  2 :  C6H:  ( OH )  8 — is  an- 
other constituent  of  madder,  also  obtained  artificially  by  oxidation  of  alizarin, 
or  from  tribromo-anthraquinone. 

Both  alizarin  and  purpurin  form  nitro-  and  amido-  substitution  products 
which  are  also  used  as  dyes;  alizarin  orange,  blue  and  brown. 

D.     DIPHENYL  AND  ITS  DERIVATIVES. 

Diphenyl,  CaH5.C«H5,  is  the  type  of  the  hydrocarbons,  known  as  phenyl- 
benzenes,  formed  by  the  substitution  of  phenyl,  toluyl,  benzyl,  etc.,  for  atoms 
of  hydrogen  in  benzene  (see  formula  of  p2-diamido-diphenyl,  p.  340).  Thus  we 
have,  besides  diphenyl,  toluyl-benzene,  C8H5.C6H4.CH3,  diphenyl-benzene, 
C«H4 :  ( C«H5 )  2,  and  triphenyl-benzene,  C8H3|  (C8H5)8.  These  hydrocarbons  are 
the  parent  substances  of  a  great  number  of  substitution  products.  The  mono- 
substituted  compounds  are  o-,  m-,  or  p-,  with  reference  to  the  point  of  union  of 
the  benzene  rings.  In  the  bi-  and  polysubstituted  derivatives  the  substituents 
may  be  introduced  into  the  same  or  into  different  rings.  Bi-substitution  of 
bivatent  groups  for  H2  in  the  ©-oppositions  produces  compounds  belonging  to 
other  series  of  our  classification. 

Diphenyl — Phenylbenzene — C6HS.C6H5 — exists    in    small    quantity    in    gas- 
tar.    It  is  formed  by  the  action  of  sodium  upon  monobromo-benzene : 
2C8H5Br-fNa2=CaH5.C6H5-)-2NaBr 

Or   by   passing   benzene   vapor   through    a   red-hot    tube;    or    by   the    inter- 
action of  diazobenzene  chloride  and  benzene  in  presence  of  aluminium  chloride: 
CaH5.N:NCl-fC6H6=  C^.C^+HCl+N, 

It  crystallizes  in  large  plates;  f.p.  70°;  b.p.  254°;  soluble  in  glacial  acetic 
acid  and  in  amylic  alcohol.  Nascent  hydrogen  converts  it  into  tetrahydro- 
diphenyl,  CJ2H14.  With  methylene  chloride,  in  presence  of  A1C1,  it  forms 

fluorene :  

C6H6.CaH6-}-CH2Cl2=CaH4.CH2.C8H4+2HCl 

E.    DIPHENYL-PARAFFINS,  DIPHENYL-OLEFINES, 
DIPHENYL-ACETYLENES. 

The  hydrocarbons  of  this  series  may  be  considered  as  derived  from  the 
aliphatic  hydrocarbons  by  substitution  of  two  (or  more)  phenyl  groups  for 
hydrogen : 

CaH5.CH8 — Phenyl  -methane =Toluene=Methyl  -benzene  (p.  342). 

C6HB.CH2.C6H5 — Diphenyl-methane=Benzyl-benzene  (formula  p.  340). 

( C8H5 )  2 :  CH.C8H5— Triphenyl-methane. 

(C«H5),:Si:  (C8H5)2 — Tetraphenyl-silicon    (C  compound  unknown). 

CflH5.CH2.CH2.CaH5— Sym.  Diphenyl-ethane=Dibenzyl. 

( CaH8 )  2 :  CH.CH8 — Unsym.   Diphenyl-ethane. 

C.H6.CH :  CH.CflH5— Sym.  Diphenyl-ethylene=Stilbene. 

C,Hs.CE:Diphenyl-acetylene=Tolane. 

Diphenyl-methane — Benzyl-benzene — is  produced  by  the  action  of  benzyl 
chloride  upon  benzene  in  presence  of  aluminium  chloride: 

C.H..CH2.C1 + C«Ha=  C«H6.CH2.C6H6+HC1 


PHENOLS   AND  ALCOHOLS  389 

It  is  a  crystalline  solid;  f.  p.  27°;  b.  p.  262°;  soluble  in  alcohol,  ether,  and 
chloroform  ;  has  an  odor  resembling  that  of  the  orange. 

Triphenyl-methane  —  is  formed  by  the  action  of  chloroform  upon  benzene  in 
presence  of  aluminium  chloride: 

3C6H6-|-CHC1,=  (  C«H5  )  2  :  CH.C»H5-f-3HCl 

It  is  a  crystalline  solid;  f.  p.  92°;  b.  p.  360°;  soluble  in  ether  and  in 
chloroform.  It  is  converted  into  a  trinitro-derivative  by  fuming  HNO,;  and  this, 
in  turn,  is  converted  by  nascent  H  into  leuco-pararosanlin,  CH.  (  C6H4.NH2  )  8. 

Stilbene  —  Toluylene  —  Sym.  Diphenyl-ethylene  —  is  formed  by  distillation 
of  benzyl  sulphide;  by  reduction  of  benzoic  aldehyde;  or  by  distillation  of  the 
phenylic  esters  of  fumaric  or  cinnamic  acids.  It  forms  large,  glistening  prisms 
or  plates;  f.  p.  124°;  b.  p.  306°.  It  forms  a  number  of  haloid  and  other 
derivatives. 

PHENOLS  AND  ALCOHOLS. 

Phenolic  derivatives  of  these  hydrocarbons  are  known,  which  contain 
hydroxyls  in  one  or  more  of  the  phenyl  groups. 

Dipkenyl  Carbinol—  Benzhydrol  —  CeHs.CHOH.C^—  is  the  simplest  -  alco- 
hol of  this  series.  It  is  formed  in  colorless  crystals;  f.  p.  68°;  b.  p.  298°;  by 
reduction  of  benzophenone  with  sodium  amalgam,  C6H5.CO.C«H8-}-H,= 


Triphenyl  Carbinol,  (  C<>H5  )  3C.OH,  and  diphenyl-m-toluyl  carbinol, 
BsJjtCfOHj.CaH^CHj^,  are  alcohols,  whose  triamido-derivatives  are  pararo- 
sanilin  and  rosanilin.  They  are  formed  by  oxidation  of  the  hydrocarbons. 
Triphenyl  carbinol  is  the  principal  product  of  the  action  of  CO2  on  phenyl  mag- 
nesium bromide.  In  the  first  stage  of  the  reaction: 

C8H5.MgBr+C02=C6H5.COO.Mg.Br;    then 

C8H5.COO.Mg.Br-f2C6H5.Mg.Br=(C<^B5)3=C.O.MgBr-(-MgO-fMgBr1  and  then 
(  C«H5  )  ,;CO.Mg.Br-f  H,O=  (  C.H5  )  ,:COH-|-HO.Mg.Br 

These  reactions  are  somewhat  similar  to  those  by  which  tertiary  aliphatic 
alcohols  are  produced  by  acidyl  halides  and  oxides  (see  No.  10,  p.  213).  They 
form  nitro-  and  amido-derivatives  of  technical  importance. 

HETEROCYCLIC    COMPOUNDS. 

These  compounds  differ  from  the  carbocyelic  in  that  they  contain 
elements  other  than  carbon  as  constituents  of  the  nuclei.  They 
form  series  parallel  to  the  carbocyelic,  from  which,  indeed,  they  may 
be  considered  as  being  derived  by  substitution  in  the  rings.  Thus 
thiophene  corresponds  to  pentole,  pyridine  to  benzene,  and  quinoline 
to  naphthalene: 

H  H       H 

C  C        C 

/\\  //\    /\\ 

HC        CH  HC        C        CH 

HC        CH  HC        C        CH 

\//  \\/    \// 

C  C        C 

H  H       H 

Pentole.  Benzene.  Naphthalene. 


390  TEXT-BOOK   OF   CHEMISTRY 

H        H 
H  C         C 

C  //\    /\\ 

/\\  HC        C        CH 
HC  -  CH                     HC        CH 

II  HC        C        CH 
HC            CH                     HC        CH  \\/    \// 

\     /  \//  C        N 

S  N  H 

Tbiophene.  Pyridine.  Quinoline. 

The  elements  which  can  be  thus  introduced  into  a  cyclic  nucleus 
are  few;  oxygen,  sulphur,  selenium,  phosphorus  and  nitrogen  being 
the  only  ones  now  known  to  enter  into  such  formation,  and  of  these 
the  nitrogen-containing  compounds  are  far  the  most  numerous  and 
the  most  important.  The  facility  with  which  the  N  atom  takes  the 
place  of  the  methine  group,  —  CH=,  in  the  benzene  ring  is  to  be 
anticipated  from  their  equivalence.  Pyridine  also  resembles  benzene 
in  its  general  characters,  and,  on  the  other  hand,  the  five  membered 
compounds,  furfurane,  thiophene  and  pyrrole,  have  general  charac- 
ters similar  to  those  of  benzene,  from  which  they  may  be  considered 
as  being  derived  by  substitution  of  the  bivalents  0,  S,  and  NH  for 
one  of  the  three  acetylenes,  —  CH:CH  —  ,  of  benzene.  The  number 
of  hetero-atoms  which  may  be  contained  in  the  nucleus  is  not 
limited  to  one,  and  five  and  six  membered  rings  containing  as  many 
as  four  nitrogen  atoms,  the  tetrazoles  and  tetrazines,  are  known. 

A  classification  of  the  heterocyclic  compounds  requires  many 
subdivisions,  because  of  the  great  number  and  variety  of  these  sub- 
stances, due  to  the  presence  of  one  or  more  atoms  of  one  or  more 
of  the  elements  above  mentioned,  in  three,  four,  five  or  six  mem- 
bered rings,  contained  in  mono-,  di-,  tri-,  or  tetra-nucleate  mole- 
cules, in  which,  also,  differences  in  the  ring-valence  are  caused  by 
differences  in  internal  linkage.  A  broad  classification  may,  however, 
be  here  followed,  somewhat  similar  to  that  for  the  aromatic  sub- 
stances (p.  339). 

A.  Mono-nucleate  compounds  :  containing  a  single  nucleus.  These 
may  be  subdivided  into  :(a)  Substances  containing  three-membered 

H2C\  H2C\ 

rings;  such  as  ethylene  oxide,       I     0,  sulphide,       I      S,  and  imide, 

H2C/  H2C/ 

H2C\ 

NH. 


(6)   Four-membered    compounds,    such    as    trimethylene    oxide, 
H2C-0  H2C-0  H2C-CHa 

I     ,  thetin,   |     |      ,  and  trimethylene  imide, 
HaC-CH2  H2C-S  HJC-NH 

HC=CH\ 
(c)    Five-membered   substances,  such    as    furfurane,  0, 

HC=CH/ 

HC=CH\  HC=CH\ 

thiophene,  S,  and  pyrrole,       |  NH. 

HC=CH/  HC=CH/ 


FIVE    MEMBERED    HETEROCYCLIC   RINGS  391 

HC-CH=CH 

(d)  Six-membered    compounds,     such    as    pyridine,    || 

HC— CH=N 

H2C-CHa-CHa  N=N— CH 

piperidine,      I  |     ,  and  sym.  tetrazine,     I 

H2C-CH2-NH  HC=N— N 

The  five-  and  six-membered  compounds  are  much  more  numerous 
and  important  than  the  three-  and  four-membered. 

B.  Condensed  compounds,  containing  two  or  more  rings,  usually 
five-  or  six-membered,  of  which  at  least  one  is  heterocyclic,  fused 
together,   and  having  two   carbon  atoms  in  common.     These   com- 
pounds,   which   correspond   to    the    condensed    benzenic    compounds 
(p.  385),  include  the  indole,  quinoline,  authraquinoline,  quinquino- 
line,  and  diphenylene  derivatives. 

C.  Compounds  containing  two  (or  more)  nuclei,  one  at  least  hete- 
rocyclic,  united  directly  without  fusion,   corresponding  to  the   di- 
phenyls,   and  including  phenyl-pyridyl,   dipyridyl,   pyridyl-pyrrole, 
and  pyridyl-piperidyl  derivatives. 

D.  Compounds  containing  two    (or  more)    nuclei,   one   at  least 
heterocyclic,    united    by    aliphatic    groups,    corresponding    to    the 
diphenyl-paraffms,    and    including    the    " ester-alkaloids"    such    as 
atropine,  cocaine,  etc. 

In  a  more  detailed  classification  the  members  of  the  several  classes 
are  subdivided  into  the  groups,  of  mono-,  di-,  tri-,  and  tetrahetero- 
atomic  compounds,  according  as  they  contain  one,  two,  three  or  four 
atoms  other  than  carbon,  of  like  or  different  kinds,  in  the  ring. 


A.— MONONUCLEATE  HETEROCYCLIC  COMPOUNDS. 
FIVE  MEMBERED  RINGS. 

The  parent  substances  of  these  compounds  are  furfurane,  thio- 
phene,  and  pyrrole  (see  p.  390). 

The  heterocyclic  rings  differ  from  the  carDocyclic  in  that  the 
several  carbon  atoms  are  not  equal  in  value,  and  therefore  two  dif- 
ferent  monosubstituted   deriva- 
tives exist  for  the  five-membered 
/  y  \\          rings  containing  a  single  hetero- 
/S'HC          CH/J   atom,   such   as   furfurane,    and 
H[]          (JH     three   such   compounds   in   six- 
a'\    //  a       membered  rings,  such  as  pyri- 
dine, according  to  the  position 

Pyridine.  '  .     *  v, 

of  substitution  with  reference 
to  the  hetero-atom.  These  positions  are  distinguished  by  the  first 
three  letters  of  the  Greek  alphabet,  as  shown  in  the  margin,  or, 
sometimes  by  numbers.  The  positions  «  and  «',  and  §  and  ft'  are 
of  equal  value. 


392  TEXT-BOOK   OF   CHEMISTRY 

HC=CH\ 

Furfurane —    1  0 — exists  in  the  product  of  distillation  of 

HC=CH/ 
pine  and  fir  wood,  and  is  also  formed  by  distillation  of  barium  pyro- 

HC— CH2\ 
mucate  (below),  and  from  dihydrofurfurane,  0,  a  product 

HC-CH2/ 

of  reduction  of  erythrol  (p.  224).  It  is  a  liquid;  b.  p.  32°;  having 
a  peculiar  odor.  Its  vapor  colors  a  pine  shaving  moistened  with 
HC1  green  (pp.  346,  393). 

HC=C— CHO 
a-Furfuraldehyde — Furfurole — Furfural — Furole — 

HC=CH— O 

is  produced  by  the  dry  distillation  of  sugar  or  of  wood;  by  the  dis- 
tillation of  these  substances,  or  of  bran,  carbohydrates  or  glucosides 
with  dilute  H2S04;;  by  the  action  of  the  concentrated  acid  upon  car- 
bohydrates; and  by  distilling  pentoses  (p.  247),  or  glucuronic  acid 
(p.  266)  with  HC1.  It  is  a  colorless  liquid;  agreeable  in  odor;  b.  p. 
162°;  soluble  in  water  and  in  alcohol.  Being  an  aldehyde,  it  under- 
goes the  reactions  common  to  those  substances.  In  concentrated 
solution,  with  urea  and  a  trace  of  acid,  it  is  colored  yellow,  changing 
to  blue,  to  violet  and  to  purple,  and  finally  fading,  with  formation 
of  a  black  precipitate  (Schiff's  reaction).  It  produces  a  red  color 
with  aniline,  a  very  sensitive  reaction  for  its  presence.  Paper  moist- 
ened with  aniline  acetic  solution  is  used.  Pettenkof  er 's  reaction  for 
the  biliary  salts,  etc.,  depends  upon  the  formation  of  furfurole. 

HC=C— COOH 
a-Furfurane   Carboxylic    Acid — Pyromucic  acid — 

HC=CH— 0 

— the  acid  corresponding  to  furfurole,  is  produced  from  that  sub- 
stance by  oxidation,  also  by  distillation  of  mucic  and  isosaccharic 
acids  (p.  265).  It  is  a  solid;  f.  p.  134°. 

HC=CH\ 
Thiophene —    |  S —  and  its  superior  homologues,   methyl- 

HC=CH/ 

thiophenes,  etc.,  occur  in  gas-tar,  and  accompany  the  various  prod- 
ucts, benzene,  etc.,  obtained  from  it.  It  is  a  colorless  liquid;  b.  p. 
84°;  which  is  so  nearly  that  of  benzene,  80.5°,  that  the  two  sub- 
stances cannot  be  separated  by  distillation.  With  sulphuric  acid 
and  isatine  it  gives  a  fine  color,  due  to  formation  of  indophenine. 
Sulphuric  acid  alone  is  colored  brown  by  thiophene,  which  it  absorbs ; 
and  thiophene  may  be  recovered  from  the  solution  by  neutralization 
and  distillation. 

HC=CH\ 
Pyrrole —    I  NH — exists   in   coal-tar  and   accompanies   the 

HC=CH/ 

pyridine  bases  (p.  397)  in  oil  of  Dippel.  It  is  formed  in  a  great 
variety  of  reactions,  as  by  the  action  of  baryta  at  150°  upon 
albumins,  by  the  dry  distillation  of  gelatin  or  of  ammonium  saccha- 
rate,  etc.  It  is  a  colorless,  oily  liquid,  having  the  odor  of  chloro- 
form; b.  p.  131°.  Being  a  secondary  amine,  it  has.  basic  properties, 


FIVE   MEMBERED   HETEROCYCLIC   RINGS  393 

and  its  imide  hydrogen  is  readily  replaced  by  other  atoms  or  groups. 
A  pine  shaving  moistened  with  HC1  is  colored  flame-red  by  pyrrole 
(the  pine-shaving  reaction;  see  also,  Phenol,  p.  346).  It  also  yields 
an  indigo-blue  color  with  H2S04  and  isatine.  Heated  with  dilute 
acids  it  gives  off  ammonia,  and  a  red  powder  (pyrrole  red)  is 
deposited. 

The  homologous  pyrroles,  methyl-pyrroles,  etc.,  have  reactions 
similar  to  those  of  pyrrole. 

Hydropyrrole    Derivatives — Nascent    hydrogen    combines    with 

CH  :CH  \ 
pyrrole  to  form,  first  dihydropyrrole,  or  pyrroline,     I  NH, 

CH2.CH2/ 
an  alkaline  liquid,  soluble  in  water;  b.  p.  91°;  and,  finally,  tetra- 

CH2.CH2\ 
hydropyrrole,  or  pyrrolidine,  or  tetramethylene-imine,  I  NH, 

which  bears  the  same  relation  to  pyrrole  that  piperidine  does  to 
pyridine  (p.  398).  Pyrrolidine  resembles  piperidine  in  its  reactions, 
and  also  forms  an  addition  product  with  methyl  iodide.  It  is  formed 
by  heating  tetramethylene-diamine  hydrochloride : 

H2N.  ( CH2)  4.NH2.HC1=NH4C1+  ( CH2)  4  :NH 

and  constitutes  the  nucleus  of  the  hygrines  and  one  of  those 
of  nicotine.  It  is  a  strongly  alkaline  liquid;  b.  p.  87°.  Among 
the  derivatives  of  pyrrolidine  is  pyrrolidone,  or  butyrolactam, 
CH2.CH2\ 

NH,   a  simple  cyclic  imide   derived  from  ^-amidobutyric 
CH2.CO/ 
acid. 

a  Pyrollidine  Carboxylic  Acid — Proline — is  a  product  of  hydroly- 
sis, by  HC1  or  by  tryptic  digestion,  of  casein  and  gelatin,  in  which  it 
probably  exists  as  a  dipeptide,  constituted  by  substitution  of  the 
radical  of  tf-amido-isocaproic  acid  for  the  imide  hydrogen  of  the 
cyclic  compounds : 

H8C\  /CH2.CH2 

CH.CH2.CH.CO.N  | 

H2N  HOOC/CH  -CH2< 
AZOLES  AND  THEIR  DERIVATIVES. 

The  azoles  are  derivable  from  furfurane,  thiophene  and  pyrrole 
by  substitution  of  one  or  more  N  atoms  for  methine  groups  in  the 
five-membered  ring.  They  are  distinguished,  according  to  their 
parent  substances,  into  furazoles,  thioazoles,  pyrroazoles  and  selen- 
azoles,  there  being  nine  possible  of  each  class,  or  they  may  be  con- 
sidered as  derived  from  pyrrole  by  substitution  of  further  hetero 
atoms  in  the  ring.  They  are  further  distinguished  as  monazoles,  dia- 
zoles,  triazoles  and  tetrazoles,  according  to  the  number  of  intro- 
duced N  atoms.  Thus  the  formulas  of  pyrrole  and  of  the  nine  pyrro- 
azoles are: 


394 


TEXT-BOOK   OF   CHEMISTRY 


HC- 

HiJ 


CII 


\    / 

N 

H 

Pyrrole. 


[JHC  -  CH[3] 

[5]HC        N[2] 
\   / 
N[J 
H 

a-Monazole. 


H 


HC  CH 

HC  N 

J    Jl 

HC        U 

\   / 

\   / 

N 

N 

H 

H 

a-a'  Diazole. 

a-/3-Diazole. 

N 


N 


i±\^  J.TI 

N        CH 

AAV>  -L'*                                  J 

N        N              1 

TI  ia 

J    U* 

II         II 
N        N 

\   / 

\   / 

\  / 

\   / 

N 

N 

N 

N 

H 

H 

H 

H 

a'-0  -Diazole. 

a'-a-/3-Triazole.       a-/3-/3'-Triazole. 

Tetrazole. 

\  / 

N 

H 

/3-0'  -Diazole. 

Corresponding  to  each  of  these  compounds  there  are  numerous 
derivatives,  formed  by  substitution,  or  by  modification  of  internal 
linkages  and  addition. 

Antipyrine — i-Phenyl-2,3-dimethyl  Pyrazolon — (formula  below) 
—is  formed,  as  its  hydroiodide,  by  heating  1,  3-phenylmethyl  pyra- 
zolon, with  methyl  iodide  and  methylic  alcohol  to  100°  in  sealed 
vessels.  In  this  reaction  the  I-pyrazolon  type  is  maintained  in  the 
product  of  addition,  but  on  splitting  off  HI  to  liberate  the  free  base 
the  antipyrine  type  is  produced : 


H2C  —  C. 
O.J        II 

\/ 

N 

CeH8 

l-phenyl-3-metbyl 
pyrazolon. 


H2C  —  C.CH3 

II/CH. 
OC        N\I 
\/ 
N 

C6H6 
lodomethylate. 


HC  =  C.CH3 
OC        N.CHs 


N 
CaH5 

Antipyrine. 


Antipyrine  forms  colorless,  odorless  scales,  somewhat  bitter  in 
taste ;  f .  p.  110.5  °.  A  mixture  of  equal  parts  of  antipyrine  and  anti- 
febrin  (f.  p.  112.5°)  fuses  at  45°.  Antipyrine  is  readily  soluble  in 
water,  alcohol  and  chloroform,  less  soluble  in  ether.  With  nitrous 
acid  or  the  nitrites  (sp.  seth.  nitr.),  in  the  presence  of  free  acid,  it 
forms  a  green,  crystalline,  sparingly  soluble  nitro-derivative,  which 
is  poisonous.  Its  solution  is  colored  deep  red-brown  by  FeCl3,  the 
color  being  discharged  by  H2S04.  Nitrous  acid  colors  its  solutions 
bright  green,  and  on  heating  the  mixture,  after  addition  of  a  drop  of 
fuming  nitric  acid,  the  color  changes  to  light-red,  then  to  blood- 
red,  and  finally  a  purple  oil  is  deposited.  Addition  of  a  drop  of 
fuming  nitric  acid  to  cold,  concentrated  solution  of  antipyrine  causes 
precipitation  of  small,  green  crystals.  Antipyrine  is  strongly  basic, 
and  some  of  its  salts  are  used  in  medicine :  Salipyrine  is  antipyrine 
salicylate.  It  is  formed  by  the  action  of  the  acid  and  the  base  upon 
each  other  at  100°.  It  is  a  white,  crystalline  powder,  almost  in- 
soluble in  water. 


FIVE    MEMBERED   HETEROCYCLIC   RINGS  395 

Tolypyrine — i-toluyl-  2,  3-dimethyl  pyrazolon — is  obtained  in 
the  same  manner  as  antipyrine,  using  p-toluyl-hydrazine  in  place  of 
phenyl-hydrazine  and  contains  toluyl,  C6H4.CH3  in  place  of  phenyl. 
It  forms  colorless  crystals ;  f .  p.  136  ° ;  and  has  a  physiological  action 
similar  to  that  of  antipyrine. 

HydantoVn,  —  Glycolylurea  —  2,  5-diketotetrahydroglyoxalin  — 
(formula  below)  is  the  simplest  of  the  cyclic  monureides  (p.  316), 
and  is  formed  by  the  action  of  HI  upon  allantoi'n,  or  upon  alloxanic 
acid.  It  is  converted  into  the  corresponding  open  chain  compound, 
hydantoic,  or  glycoluric  acid,  H2N.CO.NH.CH2.COOH,  by  heating 
withBa(OH)2. 

Corresponding  to  hydantoi'n  are  a  number  of  substituted  hydan- 
toi'ns,  constituted  by  substitution  of  alkyls  for  H  in  the  several  posi- 
tions. The  /^-compounds  are  formed  by  heating  the  monoalkyl  amido- 
acids  with  urea.  Thus  urea  and  sarcosine  yield  (3  -methylhy dantoin  * 

/CO.N.CH, 

H2N.CO.NH2+CH2  (NH.CH3)  .COOH=HN  +NH3+H20 

\CO.CH2 


OC        CO  OC        CO  OC        CO  OC        CO 

\/  \/  \/  \/ 

N  N  N  N 

H  H  H  H 

Hydantoin.  Allantoin.  Allanturic  acid.  Oxalylurea. 

Allantoin, — Glyoxyldiureide — (formula  above) — a  derivative  of 
hydantoi'n,  occurs  in  the  allantoic  fluid  of  the  cow,  in  the  urine  of 
sucking  calves,  of  dogs  and  cats  fed  on  meat,  of  children  during  the 
first  few  days  of  life,  of  adults  after  administration  of  tannin,  and  of 
pregnant  women ;  also  in  beet  juice.  It  is  also  formed  during  autoly- 
sis  of  pancreas,  liver  and  spleen.  It  is  obtained  by  oxidation  of  uric 
acid  by  lead  peroxide: 

2C5H4N403+2H20+02=2C4H6N403+2C02 

Or,  synthetically  from  glyoxylic  acid  and  urea: 

/CO.NH  m 

CHO.COOH+2H2N.CO.NH2=HN          |  +2H20 

\CO.CH.HN.CO.NH2 

It  crystallizes  in  prisms,  sparingly  soluble  in  cold  water,  readily 
soluble  in  hot  water  and  in  alcohol.  On  reduction  by  HI  it  yields 
hydantoi'n  and  urea.  Heated  with  alkalies  it  is  decomposed  into  am- 
monia and  carbonic,  oxalic  and  acetic  acids ;  glyoxylic  acid  being  prob- 
ably first  formed  and  decomposed.  Warmed  with  Ba(OH)2,  or  with 
Pb02,  it  splits  off  urea  and  forms  allanturic  acid  (formula  above). 

Oxalylurea, — Parabanic  Acid — 2,  4,  5-triketotetrahydroglyoxalin 
— (formula  above)  is  formed  by  oxidation  of  uric  acid  or  of  alloxan 


396  TEXT-BOOK   OF   CHEMISTRY 

by  HN03 ;  or  synthetically  by  the  action  of  POC13  or  PC13  on  a  mix- 
ture of  oxalic  acid  and  urea: 

/CO.NH 
COOH.COOH+H2N.CO.NH2r=HN  +2H..O 

\CO.CO 

Its  salts  are  converted  into  oxalurates  by  water. 
Histidin — C6H9N302 — one  of  the  hexon  bases,  is  produced  by 
hydrolysis  of  proteins.  It  crystallizes  in  rhombic  plates  or  needles,  is 
sparingly  soluble  in  water,  insoluble  in  alcohol  and  ether  and  is 
dextrorotary.  It  is  only  faintly  alkaline,  but  expels  C02  from  Ag 
and  Cu  carbonates.  By  oxidation  by  KMn04  in  alkaline  solution  it 
yields  HCN,  C02  and  NH3,  but  it  is  not  attacked  by  KMn04+H,S04. 
When  boiled  with  Ba(OH)2  it  does  not  give  off  NH3.  It  does  not  give 
the  biuret  reaction.  It  contains  two  H  atoms  replaceable  by  metals, 
and  it  forms  two  series  of  salts  with  acids.  Nitrous  acid  separates  one 
N  atom  as  free  nitrogen,  and  it  forms  one  substitution  product  with 
fi -naphthalene  sulphonic  acid;  but  two  of  its  N  atoms  are  capable  of 
salt  formation.  It  therefore  contains  one  NH,  and  one  NH,  and  the 
third  N  is  tertiary.  When  heated  it  gives  off  C02,  and  leaves  a  com- 
pound C5H7N2.NH2,  and  therefore  it  contains  a  COOH.  The  small 
proportion  of  H  indicates  a  closed  chain  nucleus,  and  its  reactions 
indicate  two  double  linkages  in  the  ring.  It  gives  the  Weidel  reac- 
tion faintly.  When  diazobenzene-sulphonic  acid  (C6H5.N:N.S03H, 
or  sulphanilic  acid  and  KN02 :  the  diazo  reaction)  is  added  to  a  solu- 
tion of  histidin  in  Na2C03,  a  coloring  matter  is  formed  which  is 
orange  in  acid  solution  and  dark  cherry-red  in  alkaline  solution. 
The  only  other  product  of  protein  hydrolysis  which  gives  this  reaction 
is  tyrosin.  Histidin  is  a  derivative  of  glyoxaline,  whose  constitution 

//CH.NH 
is   probably   N  ,  ft.    glyoxaline  of.    amido-pro- 

\CH  :C.CH2.CHNH2.COOH 
pionic  acid. 

SIX  MEMBERED  RINGS. 

Six   membered   heterocyclic   compounds    are   known,    containing 
oxygen,  sulphur  and  nitrogen  in  the  nucleus: 


H 

H2 

H 

H2 

C 

C 

C 

C 

N 

II  \ 

/\ 

/\ 

/\ 

/\ 

HC        CH 

HC        C.CH3 

HC        CH 

H2C         CH2 

HC        CH 

oci      HH 

M         II 
HC        CH 

nil      C!H 

H2C         CH2 

1  1  (                     '      1  1 

\/ 

\  II 

\  II 

\/ 

\  II 

o 

S 

N 

N 

N 

H 

o-Pyrone. 

0-  Methylpenthiophene. 

Pyrldlne. 

Plperldlne. 

Pyrazlne. 

The  oxygen  and  sulphur  compounds  are  neither  numerous  nor 
important.  Some  of  the  former  are  products  of  condensation  of  ali- 
phatic compounds,  tf-lactones  and  tf-anhydrides. 


SIX   MEMBERED   HETEROCYCLIC   RINGS  397 


Pyrone  (y)  —  Pyrocomane  —  0  \rijZ  c.g;*  CO  —  is  an  oxidized  derivative  of 
y  furane,  produced  from  comenic  acid  by  the  action  of  heat  and  constituting 
the  nucleus  of  comenic,  chelidonic,  and  meconic  acids. 

Comenic  acid  —  C5H2O2  (  OH  )  .COOH  —  is  produced  by  the  action  of  hot  H20, 
of  dilute  acids,  or  of  bromine  water  upon  meconic  acid.  It  crystallizes  in 
yellowish  prisms,  rather  soluble  in  H20.  It  is  monobasic.  It  is  decomposed  by 
heat  into  C02  and  pyrone. 

Chelidonic  acid  —  C5H2O2  (  COOH  )  2  —  exists  in  chelidonium,  in  combination 
with  the  alkaloids  sanguinarine  and  chelidonine.  It  is  a  crystalline  solid  and 
a  dibasic  acid.  Heat  converts  it  into  comenic  acid,  which  in  turn  yields  pyrone. 

Meconic  acid  —  C5HO2(OH)  (COOH)2  —  is  peculiar  to  opium,  in  which  it 
exists  in  combination  with  a  part,  at  least,  of  the  alkaloids.  It  crystallizes  in 
small  prismatic  needles;  acid  and  astringent  in  taste;  loses  its  Aq  at  120°; 
quite  soluble  in  water,  soluble  in  alcohol,  sparingly  soluble  in  ether. 

With  ferric  chloride  it  forms  a  blood-red  color,  which  is  not  discharged 
by  dilute  acids  or  by  mercuric  chloride;  but  is  discharged  by  stannous  chloride 
and  by  the  alkaline  hypochlorites. 

PYRIDINE  BASES  AND  THEIR  DERIVATIVES. 

The  pyridine  bases,  closely  related  to  the  vegetable  alkaloids  (p. 
419)  as  well  as  to  some  of  the  basic  substances  formed  during  putre- 
faction, were  first  obtained  from  oil  of  Dippel,  or  bone-oil  (Oleum 
animale),  an  oil  produced  during  the  dry  distillation  of  bones,  horns, 
etc.,  and  as  a  by-product  in  the  manufacture  of  ammoniacal  com- 
pounds from  those  sources.  They  also  occur  in  coal-tar,  naphtha, 
commercial  ammonia,  methylic  spirit  and  fusel  oil.  They  are  formed 
synthetically:  (1)  By  heating  the  aldehyde-ammonias  alone,  or  with 
aldehydes  or  ketones;  (2)  From  pyrrole  by  the  action  of  K  or  Na 
in  presence  of  methylene  iodide,  etc.;  (3)  By  oxidation  of  hexa- 
hydropyridines,  piperidines;  also  by  other  methods. 

The  pyridine  bases  are  colorless  liquids  of  peculiar,  penetrating 
odor.  The  superior  homologues  are  metameric  with  the  anilines. 
They  are  strong  triacid  bases,  and  behave  like  tertiary  monamines. 
Oxidizing  agents  do  not  attack  pyridine,  nor  the  nucleus  of  its  supe- 
rior homologues,  but  the  lateral  chains  of  the  picolines,  etc.,  are 
readily  oxidized,  with  formation  of  carbopyridic  acids.  Reducing 
agents  convert  them  into  piperidines  (p.  398).  They  react  with  sev- 
eral of  the  general  reagents  for  the  alkaloids  (p.  421).  The  two 
most  nearly  characteristic  properties  of  the  pyridine  bases  are:  (1) 
the  formation  of  chloroplatinates  such  as  (C5H5N.HCl)2PtCl4,  which 
on  boiling  with  water,  lose  two  molecules  of  HC1  to  form  "  modified 
salts"  such  as  (C5H5N)2PtCl4  (Anderson's  reaction),  and,  (2)  the 
formation  of  crystalline  addition  products,  alkyl-pyridinium  iodides, 
such  as  C5H5N<^HiJ  on  contact  of  their  alcoholic  solutions  with 
alkyl  iodides. 

Pyridine—  HC/£H:CH\N_is  obtained  from  oil  of  Dippel,   or 

from  piperidine.    It  boils  at  115°,  mixes  with  water  in  all  proportions, 


398  TEXT-BOOK   OF    CHEMISTRY 

is  strongly  alkaline  in  reaction.  Its  hydrochloride  is  crystalline,  but 
deliquescent.  Its  chloroplatinate  fuses  at  240°.  When  reduced  by 
sodium  and  alcohol,  it  forms  piperidine,  or  hexahydropyridine ;  and 
when  reduced  by  hydriodic  acid,  normal  pentane,  CH3.CH2.CH2.- 
CH2.CH3. 

Pyridine  Homologues — Alkyl  Pyridines — are  substitution  prod- 
ucts containing  alkyl  groups  for  H.  Owing  to  the  inequality  in 
value  of  the  several  C  atoms  of  pyridine  (p.  397),  the  number  of 
substituted  derivatives  is  greater  than  with  benzene.  There  are 
three  monosubstituted  derivatives,  six  each  of  the  bi-  and  tri-sub- 
stituted,  three  tetra-,  and  one  penta-substituted. 

Methyl-pyridines — Picolines— C5H4N(CH3)— The  three  pico- 
lines,  a,  ft  and  y,  exist  in  oil  of  Dippel,  and  have  been  formed  syn- 
thetically. Their  b.  p.'s  are  130°,  143°,  and  144°. 

Lutidines — Three  ethyl  pyridines,  C5H4N(C2H5),  are  known,  or, 
b.  p.  148°,  yff,  b.  p.  166°;  and  y,  b.  p.  165°.  Of  the  six  possible 
dimethyl-pyridines,  C5H3N(CH3)2,  four  are  known,  three  of  which 
exist  in  bone  oil. 

Collidines — CgH^N — There  are  twenty-two  possible  collidines,  of 
which  twelve  are  known.  Of  these  several  are  products  of  decom- 
position of  vegetable  alkaloids,  or  exist  in  oil  of  Dippel,  or  are  pro- 
duced during  putrefaction. 

Hydropyridines — Piperidines — are  compounds  produced  from  the 
pyridines  by  the  action  of  nascent  hydrogen.  Dihydropyridines  and 
tetrahydropyridines  are  known,  the  latter  known  as  piperideines, 
but  by  far  the  most  important  of  the  group  is 

Piperidine— Hexahydropyridine— H2C  \c!22'cH22/NH  ~~  which  is 
produced  by  saponification  of  piperine  by  heating  with  alcoholic 
KOH,  and  is  also  formed  by  reduction  of  pyridine,  or  by  heating 
pentamethylene-diamine  hydrochloride.  It  is  a  colorless  liquid;  b.  p. 
106  ° ;  having  an  odor  like  that  of  pepper ;  readily  soluble  in  water 
and  in  alcohol.  Oxidizing  agents  rupture  the  piperidine  ring, 
with  formation  of  aliphatic  compounds.  When  heated  with 
methyl  iodide  it  is  converted  into  methylpiperidine  hydroiodide, 
H  C/CH2.CH2\N//HI 
n*^  \CH2.CH2/  w  \CH8.* 

Piperidine  and  methyl-piperidine  are  particularly  of  interest  as 
being  the  nuclei  of  a  number  of  vegetable  alkaloids.  Thus  coniine 
is  a  propyl-piperidine,  and  tropine  and  ecgonine,  the  basic  nuclei 
of  the  atropic  and  cocaine  alkaloids,  are  derivatives  of  methyl-piperi- 
dine (see  pp.  425,  427). 

AZINES  AND  THEIR  DERIVATIVES. 

The  azines  are  compounds  bearing  the  same  relation  to  pyridine 
that  azoles  bear  to  pyrrole  (p.  393),  i.e.,  they  are  derived  from  pyri- 
dine by  substitution  of  further  hetero-atoms  in  the  ring.  Oxygen, 


SIX    MEMBERED   HETEROCYCLIC    RINGS  399 

sulphur  and  nitrogen  are  the  only  elements  known  to  enter  into  such 
ring  formation.  When  but  one  hetero-atom  exists  in  the  ring  in 
addition  to  the  pyridine  N,  the  substance  is  a  derivative  of  an  oxazine 
if  it  is  0,  of  a  thiazine  if  it  is  S,  and  of  a  diazine  if  it  is  N;  and 
there  are  three  of  each  class,  —  ortho,  meta  and  para.  Nuclei  also  exist 
containing  more  than  two  hetero-atoms,  0,  S,  or  N,  in  a  six  mem- 
bered  ring,  and,  as  these  may  be  like  or  unlike,  such  compounds  are 
very  numerous  and  of  great  variety. 

The  oxazines  and  thiazines  are  only  known  in  their  derivatives. 

Diazines.  —  There  exist  three  isomeric  diazines  —  ortho,  meta  and 
para  —  which  are  thin,  colorless  oils,  soluble  in  water,  alcohol  and 
ether,  insoluble  in  petroleum  ether,  neutral  in  reaction: 

H  H  COOH  H 

C                            C  N                                  C                        N 

/4\\                      /4\\  /\\                                /\\                   /\ 

HC5     3CH  HC5     3N  HC       CH  HOOC.C       CH  H2C       CH2 

HC6     2N  HC6     2CH  HC       CH  HC      N  H2C       CH2 

\l//  \l//  \  II  \  //  \/ 

N  N  N  N  N 

H 

Orthodlazine.  Metadiazine.  Paradlazine.  4,5-orthodiazine  Hexahydro- 

Pyridiazine.  Pyrimidine.  Pyrazine.  dlcarboxylic    acid.  pyrazine. 

Orthodiazine  —  Pyridiazine  —  is  obtained  by  heating  the  4,  5-dicar- 
boxylic  acid  (formulas  above):  C4H2N2(COOH)2=C4H4N2+2C02, 
which  is  itself  obtained  from  the  tetracarboxylic  acid,  a  product  of 
oxidation  of  phenazone  (below).  It  has  a  pyridine-like  odor,  b.  p. 
208°.  Forms  an  insoluble,  crystalline  compound  with  AuCl3. 

Metadiazine  —  Pyrimidine  —  is  obtained  by  starting  from  4-methyl- 
uracil.  This  is  first  converted  by  POC13  into  4-methyl-2,  6-dichlor- 
pyrimidine,  which  is  then  reduced  by  zinc  dust  to  4-methylpyrimi- 
dine,  which  is  then  oxidized  to  the  carboxylic  acid,  and  this  is  de- 
composed by  heat  into  pyrimidine  and  carbon  dioxide: 


HC 


Pyrimidine-4-  Pyrimidine. 

carboxylic  acid. 

The  free  base  is  an  oil,  b.  p.  124°,  having  a  penetrating,  narcotic 
odor,  which  forms  a  nitrate  and  a  hydrochloride,  both  of  which  are 
completely  volatile  below  100°.  It  forms  crystalline  compounds  with 
HgCl2,  AuCl3,  and  picric  acid,  but  not  with  CuS04. 

Paradiazine — Pyrazine — is  obtained  by  condensation  of  amido 
acetaldehyde  by  mercuric  chloride : 


400 


TEXT-BOOK   OF    CHEMISTRY 


It  has  a  faint  heliotrope  odor.  B.  p.  118°.  From  concentrated 
aqueous  solution  it  deposits  crystals,  f.  p.  53°,  which  are  extremely 
volatile.  It  forms  a  crystalline  compound  with  CuS04.  Pyrazine 
and  its  homologues  are  produced  during  fermentation,  and  exist  in 
fusel  oils  and  in  commercial  amylic  alcohol. 

Hexahydro  -  pyrazine  —  Piperazine  —  Diethylene  Diamine — 
HN.CH,.CH2 

—may  be  obtained  by  reduction  of  para-diazine,  but  is 
HjC.CH2.NH 

manufactured  from  diphenyl-diethylene  diamine,  CJEL.N  ^SS^SS2^ 

\{jtl2.L,a.2/ 

N.CeH5,  which  is  obtained  by  the  action  of  ethylene  bromide  upon 
aniline.  It  crystallizes  in  colorless  needles;  f.  p.  104°;  b.  p.  145°; 
soluble  in  water,  and  deliquescent.  It  is  strongly  alkaline  and  basic, 
and  absorbs  carbon  dioxide  from  air.  It  forms  a  soluble  compound 
with  uric  acid  and  is  used  medicinally  as  a  solvent  for  uric  acid  in 
lithiasis. 

Pyrimidine  Derivatives. — The  pyrimidine,  or  myazine  compounds 
which  are  of  medical  interest  are  not  referable  directly  to  pyrimi- 
dine, or  metadiazine  itself,  but  to  the  hydropyrimidines  (formulae 
below),  of  which  they  are  ring  ketone  derivatives,  most  of  which  con- 
tain the  grouping  N.CO.N,  which  also  exists  in  urea.  They  include 
uric  acid  and  its  derivatives,  the  xanthine  bases,  and  most  of  the 
cyclic  ureides  (p.  316).  They  are  divided  into  two  groups: 

I.  Compounds  containing  a  single  hydropyrimidine  ring,  more  or 
less  modified  by  substitution.     This  class  includes:   (a)   The  uracil 
group,  (b)  The  malonylurea  group,  (c)  The  guanides. 

II.  The  purine  group. — Compounds  containing  a  hydropyrimi- 
dine nucleus  with  a  glyoxaline  ring  fused  upon  it.    These  compounds 
would  be  more  properly  classified  among  the  condensed  heterocyclic 
compounds  (p.  414),  but  are  more  conveniently  considered  here. 

The  positions  of  orientation  in  the  pyrimidine  ring  have  been 
designated  in  several  different  ways,  which  has  led  to  no  little  con- 
fusion. The  notation  which  will  be  adopted  here  is  that  in  which 
numbers  are  used,  and  in  which  the  two  nitrogen  atoms  occupy  the 
1  and  3  positions,  as  in  the  following  formula?  of  pyrimidine  and  of 
uracil : 


H(4) 

H 

H 

Ha 

C 

C 

C 

C 

/\\ 

/\\ 

//\ 

/\ 

(1)HN—  CO  (6) 

(5)HC      N(3) 

(6)HC       CH(2) 
\// 

H2C      N 

HaC       CH 

\// 

HC      NH 

H,C       CH, 
\/ 

H2C      NH 

H2C       CHa 
\/ 

(2)  OC     CH(5) 
(3)HN—  CH(4) 

N 

N 

N 

N 

(1) 

H 

H 

Pyrimidine. 

Al,  3-Dihydro- 

A  4-Tetrahydro- 

Ilexahydro- 

2,    6  M-Diketotet- 

pyrimldine. 

pyrimidine. 

pyrimidiue. 

rahydropyrlm- 
idine    (Uracil). 

SIX   MEMBERED   HETEROCYCLIC   RINGS  401 

While  the  above  hexagonal  expressions  are  most  in  conformity 
with  those  of  other  cyclic  compounds,  and  are  on  that  ground  prefer- 
able to  ^the  quadrilateral  expression  of  the  formula  of  uracil,  the 
latter  form  was  adopted  for  the  uracyl,  uric  acid  and  xanthine  deriva- 
tives before  their  relationship  to  pyrimidine  was  recognized,  and  have 
since  come  into  such  universal  use  that  we  feel  reluctantly  compelled 
to  make  use  of  them  for  these  compounds. 

I  a.  The  Uracil  Group. — The  physiologically  interesting  members 
of  this  group  are  2,  6-diketo  derivatives  of  the  unknown  tetrahydro- 
pyrimidine,  sometimes  referred  to  as  oxypyrimidine  derivatives,  a  term 
which  more  properly  applies  to  compounds  containing  a  phenolic  or 
secondary  alcoholic  OH  as  a  lateral  chain. 

Uracil — C4H4N202 — 2,  6-  A  4-diketotetrahydropyrimidine — was 
first  obtained  as  a  product  of  decomposition  of  yeast-nucleic  acid,  and 
later  from  other  nucleic  acids.  It  is  also  formed  from  thymine  in 
autolysis  of  pancreas,  and  is  probably  widely  disseminated  in  animal 
organisms.  It  has  been  obtained  synthetically:  Hydrouracil,  the 
corresponding  hexahydropyrimidine  derivative,  is  first*  obtained, 
either  by  heating  together  urea  and  /?-amidopropionic  acid : 

HN.CO.NH 

H2N.CO.NH2+CH2NH2.CH2.COOH:=     |        I     +NH3+H2O 

OC.CH2  CH2 

or,  more  readily,  from  urea  and  acrylic  acid: 

HN.CO.NH 

H2N.CO.NH2+CH2  :CH.COOH=     |         I      +H20 

OC.CH2.CH2 

This  latter  reaction  constitutes  a  general  method  of  synthesis  of 
uracil  derivatives,  starting  from  various  unsaturated  acids,  known 
as  Fischer  and  Boeder's  method.  The  hydrouracil  is  then  converted 
into  a  bromine  derivative,  which  is  debrominated  by  pyridine : 

HN.CO.NH 
C4H5N202Br+C5H5N=o(j  CH^H +C5H5NHBr 

Another  general  method  of  synthesis  of  the  uracil  compounds  is 
that  of  Wheeler  and  Johnson,  based  upon  the  fact  that  alkylpseudo- 
thioureas  readily  condense  with  ketonic  acid  esters  to  form  alkyl- 
mercaptoketopyrimidines,  which  are  split  by  boiling  with  HC1  or 
HBr  to  ketopyrimidines  and  mercaptan.  Thus  ethylpseudothiourea 
and  sodium  formylacetic  ester  condense  to  2-ethylmercapto-6-keto- 
pyrimidine,  which  is  decomposed  by  HBr  to  uracil  and  mercaptan: 

HN.C(S.C2H5):N 


HN  :C  \S.C2H6  +NaO.CH  :CH.COO(  C2H5)  = 
+C2H5.OH+NaOH,  and 

HN.C(S.C2H5)  :N  HN.CO.NH 

CO.CH  = 


402  TEXT-BOOK    OF    CHEMISTRY 

Uraeil  crystallizes  in  rosettes  of  needles,  easily  soluble  in  hot 
water,  difficultly  in  cold  water,  almost  insoluble  in  alcohol  and  ether, 
easily  soluble  in  ammonia.  It  does  not  form  compounds  with  HC1  or 
HN03,  nor  a  ppt.  with  phosphotungstic  acid.  With  AgN03  alone  it 
does  not  ppt.,  but  on  addition  of  NH/)H  a  gelatinous  ppt.  is  formed, 
soluble  in  excess.  It  also  forms  a  ppt.  with  Hg(N03)2.  It  gives  the 
Weidel  reaction,  which  consists  of  the  production  of  a  red  or  purple 
color  when  chlorine  water  and  a  trace  of  HN03  are  evaporated  with 
the  substance,  and  the  residue  is  exposed  to  ammonia.  This  reaction 
is  characteristic  of  certain  pyrimidine  compounds  (see  Xanthine, 
p.  410).  Two  methyluracils  are  known. 

4-Methyluracil — (formula  p.  403) — the  earliest  known  of  the 
uracil  compounds,  is  formed  by  the  condensation  of  acetoacetic  ester 
with  urea : 

HN.CO.NH 
CH3.CO.CH2.COO(C2H5)+H2N.CO.NH2=    I        I        + 

OC.CH :  C.CHg 

C2H5.OH+H20 

a  reaction  which  constitutes  one  of  the  steps  in  a  synthesis  of  uric 
acid  (p.  406).  It  is  also  formed  by  Fischer  and  Boeder's  method 
by  starting  from  crotonic  acid,  CH3.CH  :CH.COOH ;  and  by  Wheeler 
and  Johnson's  method  by  starting  from  methylpseudothiourea  and 
acetoacetic  ester.  It  crystallizes  in  needles  from  hot  water,  and  is 
difficultly  soluble  in  alcohol.  It  dissolves  in  NaOH  or  KOH,  form- 
ing crystallizable  salts.  By  further  methylation  it  yields  dimethyl- 
and  trimethyl-uracil.  It  also  forms  chlorine,  nitro,  amido  and  phenyl 
derivatives,  and  carboxylic  acids. 

Thymine — 5-Methyluracil — (formula  p.  403) — is  a  product  of 
decomposition  of  thymus-nucleic  acid.  It  is  formed  synthetically  by 
Fischer  and  Boeder's  method,  starting  from  methyacrylic  acid, 
CH2:C(CH3).COOH;  and  by  Wheeler  and  Johnson's  method,  start- 
ing from  methylpseudothiourea  and  sodium  formylpropionic  ester, 

£8Q/C.COOH.  It  crystallizes  in  quadratic  or  six-sided  prisms; 
fuses  and  sublimes  at  250  ° ;  is  difficultly  soluble  in  cold  water,  easily 
in  hot  water,  less  soluble  in  alcohol  and  ether.  It  is  neither  distinctly 
acid  nor  basic.  Its  aqueous  solution  ppts.  with  Hg(N03)2;  with 
HgCl2  only  after  addition  of  NaOH  to  slight  alkalinity,  and  with 
AgN03  only  after  addition  of  NH4OH.  It  decolorizes  bromine  water. 
On  nitration  and  subsequent  reduction  it  yields  a  compound  which 
gives  the  Weidel  reaction.  It  is  pptd.  by  phosphotungstic  acid. 

4-Phenyluracil— C4H3N202.C0H5— is  formed  by  condensation  of 
urea  and  benzoylacetic  ester,  CH2(CO.C6H5).COO(C2H5)  ;  by  Fischer 
and  Boeder's  method,  starting  from  cinnamic,  or  /ff-phenylacryli<3 
acid,  CH(C6H5)  :CH.COOH;  and  by  Wheeler  and  Johnson's  method, 
starting  from  methylpseudothiourea  and  sodium  benzoylacetate.  5- 
Phenyluracil  is  also  known. 


SIX   MEMBERED   HETEROCYCLIC   RINGS  403 

Cytosine—  6-amido-  2  keto  -  A  4,  6-dihydropyrimidine—  (formula 
below)  —  obtained  from  thymus-imcleic  acids,  herring  and  sturgeon 
melt,  pancreas,  yeast  and  wheat,  is  not  properly  a  uracil  derivative, 
as  it  does  not  contain  two  CO  groups,  and  it  is  a  dihydro  pyrimidine, 
not  a  tetrahydropyrimidine,  derivative.  It  is  obtained  synthetically 
by  Wheeler  and  Johnson's  method:  2-ethylmercapto-6-ketopyrimidine 
is  obtained  as  described  above  (uracil).  This  is  then  converted  by 
PC15  into  2-ethylmercapto-6-chlorpyrimidine,  which  with*  alcoholic 
ammonia  produces  2-ethylmercapto-6-amidopyrimidine  : 

N.C(S.C2H5)  :N  N.C(S.C2H5)':N 


and  this  is  split  by  HBr  into  cystosine  and  mercaptan  : 
N.C(S.C2H5):N  N.CO.NH 

||  |        +H20=  |     +C2H5.SH 

CNH2.CH=CH  H2N.C.CH:CH 

Cytosine  crystallizes  in  pearly  plates,  difficultly  soluble  in  water. 
It  forms  a  hydrobromide,  chloroplatinate,  picrate,  nitrate  and  two 
sulphates,  which  are  all  crystalline.  It  is  pptd.  by  phosphotungstic 
acid,  by  AgN03,  and  by  Ba(OH)2  in  excess.  It  gives  the  Weidel  re- 
action, although  it  contains  but  one  CO.  Nitrous  acid  converts  it 
into  uracil: 

C4H5N30+HN02=C4H4N202+N2+H20 

as  guanine  is  converted  into  xanthine,  and  adenine  into  hypo- 
xanthine  (p.  411).  When  oxidized  by  BaMn208  it  yields  biuret  and 
oxalic  acid: 

C4H5N30+H20+202=C2H5N302+C204H2 

The  relations  of  the  uracils  and  cytosine  are  shown  in  the  follow- 
ing formulae: 

HN—  CO         HN—  CO         HN—  CO          N=C.NH2 
OC  CH         OC  CH         OC  C.CH3        OC  CH 
HN—  CH         HN—  C.CH3       HN—  CH         HN—  CH 

Uracil.  4-Methyluracil.  Thymine.  Cytosine. 

11}  .  The  Malonylurea  Group.  —  The  members  of  this  group  are 
tri-  or  tetraketo-hexahydropyrimidine  compounds,  all  of  which  are 
derivable  from  malonylurea  by  substitution  in  the  CH2  group  of 
malonic  acid.  The  three  principal  members  of  the  group  are  : 

HN—  CO  HN—  CO  HN—  CO 

II  II  II 

OC     CH2  .     OC     CHOH  OC    CO 

HN—  CO  HN—  CO  HN—  CO 

Malonylurea.  Tartronylurea.  Mesoxalylurea. 


404  TEXT-BOOK   OF    CHEMISTRY 

Malonylurea — Barbituric  Acid — 2,  4,  6-Triketohexahydropy- 
rimidine — C4H4N2O3 — is  produced  by  the  action  of  POC13  upon  a 
mixture  of  urea  and  malonic  acid: 

HN.CO.NH 
3H2N.CO.NH2+3COOH.CH2.COOH+2POC13=3    \ 

OC.CHj.CO 

+2P04H3+6HC1 

It  is  also  formed  by  the  action  of  concentrated  H2S04  on  allox- 
antin  (below).  It  crystallizes  with  4  Aq.,  is  efflorescent,  sparingly 
soluble  in  cold  water,  readily  soluble  in  hot  water.  It  behaves  as  a 
dibasic  acid.  It  is  decomposed  by  boiling  alkalies : 

C4H4N203+3H20=COOH.CH2.COOH+2NH3+C02 

In  malonylurea  the  hydrogen  atoms  of  the  CH2  group  exhibit  the 
same  mobility  that  they  do  in  malonic  ester,  and  are  replaceable  by 
sodium,  which  is  in  turn  replaceable  by  alkyls.  Thus  dimethyl- 

malonylurea,  OC^^CO/^01^'  mav  be  P™duced  either  by 
the  successive  action  of  Na  and  CH3I  upon  malonylurea,  or  by  the 
action  of  POC13  upon  urea  and  dimethylmalonic  acid.  The  last 
named  acid  is  produced  when  dimethylmalonylurea  is  hydrolyzed  by 
KOH.  Dimethylmalonylurea  is  isomeric  with  malonyldimethylurea, 

OC\N(CH88)'.CO/CH2»  obtained  by  the  action  of  POC13  upon  malonic 
acid  and  dimethylurea.  Diethylmalonylurea,  OC^l;£o/C(C2H5)  2, 
is  similarly  obtained,  and  has  been  used  as  a  hypnotic  under  the 
name  veronal. 

Tartronylurea — Dialuric  Acid — 2,  4,  6-triketo-5-oxyhexahydro- 
pyrimidine — C4H4N204 — is  produced,  along  with  oxaluric  acid  by 
reduction  of  alloxan,  it  containing  a  secondary  alcoholic  group  in 
the  5  position,  where  alloxan  contains  a  ketone  group  (formulae 
p.  403).  It  is  converted  by  nitrous  acid  into  allantoin.  By  exposure 
to  air  and  moisture  tartronylurea  forms  alloxantin,  C8H4N407,  in 
which  reaction  probably  one  molecule  of  tartronylurea  is  oxidized 
to  alloxan,  which  condenses  with  a  second  molecule  of  tartronyl- 
urea. Alloxantin  is  also  formed  by  reduction  of  alloxan,  and  by 
oxidation  of  uric  acid.  It  forms  sparingly  soluble  crystals,  which 
turn  red  on  exposure  to  air.  Murexide  is  the  ammonium  salt  of  the 
unknown  purpuric  acid,  C8H5N506,  derived  from  alloxantin  by  sub- 
stitution of  NH  for  0,  and,  like  that  substance,  containing  two 
hydropyrimidine  nuclei.  It  is  produced  by  heating  alloxantin  with 
NH3,  or  by  evaporating  nitric  acid  on  uric  acid,  and  adding  ammonia 
to  the  residue  (murexide  test,  p.  408).  The  product  of  the  Weidel 
reaction,  in  which  chlorine  water  with  a  trace  of  HN03  is  used  as  an 
oxidant  (p.  402),  is  also  probably  murexide.  Murexide  crystallizes 
in  short,  red  prisms,  having  a  greenish  reflection,  and  forming  a  red 


SIX   MEMBERED   HETEROCYCLIC   RINGS  405 

powder  when  ground.    It  is  difficultly  soluble  in  cold  water,  insoluble 
in  alcohol  and  ether. 

Allpxan — Mesoxalylurea — 2,  4,  5,  6-Tetraketohexahydropyrimi- 
dine — C4H2N204 — is  a  product  of  the  limited  oxidation  of  uric  acid, 
alloxantin,  or  murexide.  Uric  acid  oxidized  by  dilute  HN03  at  60  °  to 
70  °  yields  alloxan  and  urea : 

HN.CO.C.NH\  HN.CO.NH 

I  CO+H20+0=    I         |     +H2N.CO.NH2 

OC.NH.C.NH/  OC.CO.CO 

It  has  been  found  in  the  intestinal  mucus  in  diarrhea.  It  forms 
prismatic  crystals,  readily  soluble  in  water,  which  turn  red  in  air, 
are  acid  in  reaction,  and  stain  the  skin  red.  Reducing  agents  con- 
vert it  into  alloxantin ;  and  by  oxidation  it  yields  oxalylurea, : 

HN.CO.NH  HN.CO\ 

I         |    +0=     I  NH+C02 

OC.CO.CO  OC.CO/ 

When  heated  with  Ba(OH)2  the  cyclic  nucleus  is  broken,  and 
alloxanic  acid  is  formed: 

HN.CO.NH 

I         |    +H20=H2N.CO.NH.CO.CO.COOH 

OC.CO.CO 

Ic.    The  guanides  are  derivatives  of  malonylguanide,  which  is 
2-imido-4,  6-diketohexahydropyrimidine,  and  is  formed 
by  the  interaction  of  guanidine  and  malonic  ester : 
TT\T  r    JTT  /NH2 

p  COO(C2H5).CH2.COO(C2H5)+HN:C 

HN-CO  HKC(NH).NH 

Malonylguanide.  |      +  2C2H5.OH 

OC.CH2  —  CO 

The  derivatives  are  formed,  as  are  those  of  malonic  ester,  and  of 
malonylurea,  by  substitution  in  the  CH2  group. 

II.  The  purine  group. — The  compounds  of  this  group,  which  in- 
cludes uric  acid,  the  xanthine  bases,  caffeine,  etc.,  are  derivatives  of 
purine,  whose  molecule  consists  of  a  pyrimidine  ring,  with  a  glyoxalin 
ring  fused  upon  it  at  the  4  and  5  positions : 


N=CH  (1)N=CH(6) 

HC     C N  (2)HC    0(5)— NH(7) 


II  II      >*  II  II 

N— C— NH  (3)N— 0(4) 


the  last  of  which  is  the  formula  now  generally  adopted. 

Some  of  the  derivatives  are  referable  to  purine  itself,  others  to  the 
methylpurines,  in  which  CH3  is  substituted  for  H  in  one  or  more  of 
the  positions,  2,  6,  8,  and  7  or  9. 


406  TEXT-BOOK   OF   CHEMISTRY 

Purine — C5H4N4 — is  obtained  by  starting  from  uric  acid  (1). 
This  is  converted  by  POC13,  first  into  8-keto-2,  6-dichlorpurine  and 
then  into  2,  6,  8-trichlorpurine  (2).  By  the  action  of  HI  and  PHJ 
this  is  converted  into  2,  6-diiodopurine  (3),  which  by  boiling  with 
zinc  in  an  atmosphere  of  C02  yields  purine  (4)  : 


HN—  CO 
OC     C.NH\ 

N=CC1 
C1C     C.NH\ 

N=CI 
1C     C.NH\ 

N=CH 
HC     C.NH\ 

1    II         co 

HN—  C.NH/ 

II     M           CC1 

N—  C  .  N  // 

It. 

II            CH 

-C  .  N  // 

UCH 
.N// 

(1) 

(2) 

(3) 

(4) 

Purine  crystallizes  in  small  needles,  f.  p.  212°,  very  soluble  in 
cold  water  and  in  warm  alcohol.  It  is  neutral  in  reaction,  but  forms 
salts  with  both  acids  and  bases.  Its  solutions  ppt.  with  AgN03, 
phosphotungstic  acid  and  tannin;  not  with  KI,  Nessler's  reagent  or 
K4Fe(CN)0.  It  withstands  oxidizing  agents.  Its  reaction  with  Br  is 
characteristic;  in  its  solution  in  concentrated  HC1,  Br  forms  a  fine 
reddish  yellow,  crystalline  mass,  soluble  on  warming,  and  crystalliz- 
ing again  on  cooling. 

Uric  Acid — Lithic  Acid — 2,  6,  8-Triketopurine — (formula  1, 
above),  C5H4N403 — occurs  in  the  urine  of  man  and  of  the  carnivora, 
in  combination,  chiefly  as  its  disodic  salt;  in  the  urine  of  the  herbi- 
vora,  in  which  ordinarily  it  is  replaced  by  hippuric  acid,  when,  in 
early  life  and  during  starvation,  they  are,  for  the  time  being,  prac- 
tically carnivora;  in  some  urinary  calculi,  in  the  so-called  "chalky 
deposits,"  or  "tophi,"  in  the  joints  of  the  gouty;  very  abundantly 
in  the  excretions  of  serpents,  tortoises,  birds,  molluscs  and  insects, 
and  in  guano ;  in  smaller  amount  in  the  blood  and  tissues.  It  is  best 
obtained  from  guano  or  from  the  solid  urine  of  serpents,  which  con- 
sists almost  entirely  of  ammonium  urate. 

Uric  acid  is  obtained  synthetically:  (1)  From  monochloracetic 
acid  and  urea.  Monochloracetic  acid  is  converted  into  malonic  acid; 
this  is  then  condensed  with  urea  to  malonylurea  (5  below)  ;  this  by 
HN03  to  nitromalonylurea  (6)  ;  this  by  reduction  to  amidomalonyl- 
urea  (7)  ;  this  by  condensation  with  urea  to  pseudouric  acid  (8)  ; 
and  this  by  dehydration  to  uric  acid  (9) : 

H,N            COOH                         HN— CO                          HN— CO 
OC    -f    CHa  — >         OC     CH2        ^         OC     CH.NO,        > 

H,N  COOH  HN— (JO  ml— CO 

(5)  (6) 

HN— CO                                   HN— CO  HN— CO 

OC     CH.NH,         — >          OC     CH.NH.CO.NH,          ^         OC     C.NH 

HN— 00  HN-do  HN— C.NH/ 

(7)  (8)  (9) 


SIX    MEMBERED    HETEROCYCLIC    RINGS  407 

(2)  From  acetoacetic  ester  and  urea:  4-Methyluracil  is  first  obtained 
from  acetoacetic  ester  and  urea  (10  below).  By  the  action  of  fuming 
HN03  and  H2S04  this  is  converted  into  the  5-nitro-4-carboxylic 
acid  (11)  ;  this  by  heat  to  5-nitrouracil  (12)  ;  this  by  reduction  to 
a  mixture  of  5-amidouracil  (13),  and  5-oxyuracil,  or  isobarbituric 
acid  (14)  ;  the  former  of  which  is  converted  into  the  latter  by  dilute 
acids.  By  oxidation  with  bromine  water  5-oxyuracil  yields  4,  5- 
dioxyuracil,  or  isodialuric  acid  (15),  which  in  presence  of  concen- 
trated H2S04  condenses  with  urea  to  uric  acid  (16)  : 

HN— CO                   HN— CO                         HN— CO                     HN— CO 
OC     CH       ^    OC     C.NO2       >      OC     C.NO2    ^     OC     C.NH,  ^ 

HN— C.CH3  HN— C.COOH  HN— CH  HN— CH 

(10)  (11)  (12)  (13) 

HN— CO  HN— CO  HN— CO 

OC     C.OH  OC     C.OH        H2NV  _^.         OC     C.NHX 

I     II  I     II      +        /co  I     I!      /co 

HN— CH  OC— C.OH        H2N/  HN— C.NH/ 

(14)  (15)  (16) 

(3)  From  amidoacetic  acid  and  urea,  by  heating  glycocoll  with 
excess  of  urea  to  200°-230°: 

HN.CO.C.NH. 

3H2N.CO.NH2+CH2NH2.COOH=:     |  >CO+2H20+3NH3 

OC.NH.C.NH/ 

When  pure,  uric  acid  crystallizes  in  small,  colorless,  rhombic, 
rectangular  or  hexagonal  plates,  or  in  rectangular  prisms.  As  crys- 
tallized from  the  urine,  it  is  more  or  less  colored  by  the  urinary  pig- 
ments, and  the  angles  of  the  crystals  are  rounded  to  produce  lozenge 
shapes,  which  are  arranged  in  bundles,  crosses  or  daggers.  It  is  very 
sparingly  soluble  in  water,  requiring  36,480  parts  of  pure  water  for 
its  solution  at  18°.  In  ordinary  distilled  water  it  is  more  soluble,  1: 
15,000  cold,  and  1 :1,900  boiling.  It  is  soluble  in  1,900  parts  of  a  2 
per  cent,  solution  of  urea,  insoluble  in  alcohol  and  ether.  Cold  HC1 
dissolves  it  more  readily  than  water,  and  on  standing  deposits  it  in 
colorless  rectangular  plates.  Its  aqueous  solution  is  acid  to  litmus, 
but  tasteless  and  odorless.  It  also  dissolves  unchanged  in  concen- 
trated H2S04,  and  is  deposited  from  the  solution  on  dilution  with 
water.  It  dissolves  in  KOH  and  NaOH  solutions  with  formation  of 
urates. 

Uric  acid  is  decomposed  by  heat,  yielding  as  final  products  ammo- 
nia, carbon  dioxide,  urea  and  hydrocyanic  and  cyanuric  acids.  Nas- 
cent hydrogen  reduces  it  to  xanthine  (p.  410).  With  Cl,  Br,  or  I  at 
ordinary  temperatures  it  forms  oxalic  and  parabanic  acids,  alloxan 
and  ammonium  cyanate.  Heated  with  Cl  it  yields  cyanuric  acid  and 
HC1.  It  dissolves  in  cold  HN03,  with  effervescence  and  formation  of 


408  TEXT-BOOK   OF    CHEMISTRY 

alloxan,  alloxantin  and  urea;  with  hot  HN03  parabanic  acid  is  pro- 
duced. A  yellow  or  red  residue  remains  when  HN03  is  evaporated  on 
uric  acid,  and  this  assumes  a  fine  red-violet  or  purple  color  when 
moistened,  in  the  cold,  with  NH4OH,  NaOH  or  KOH  (murexide  reac- 
tion). On  heating  with  concentrated  HC1  to  170°  uric  acid  is  decom- 
posed to  glycocoll,  ammonia  and  carbon  dioxide : 

C5H4N403+5H20=CH2NH2.COOH+3C02+3NH3 

and,  as  ammonia  and  carbon  dioxide  are  the  products  of  hydrolysis 
of  urea,  this  decomposition  is  the  reverse  of  the  synthesis  described 
above  (p.  406).  When  oxidized  by  lead  peroxide  uric  acid  yields 
allantoi'n,  carbon  dioxide,  urea  and  oxalic  acid,  two  distinct  reactions 
occurring  at  the  same  time: 

HN.CO.C.NH .                                    HN.CO.CH.NH.CO.NH2. 
21         II           >  CO-f2H20+02=2       |  +2C02  and 

OC.NH.C.NH  /  OC NH 

HN.CO.C.NH  v 

\CO4-3H2O+O2=2H2N.CO.NH2+COOH.COOH+C02. 
OC.NH.C.NH  / 

Certain  bacteria   decompose  uric  acid  according  to   the   equation: 
C5H4N403+2H20+03=:3C02+2H2N.CO.NH2 

Uric  acid  is  decomposed  by  sodium  hypobromite,  giving  off  47 
per  cent,  of  its  nitrogen  in  the  cold,  or  the  whole  when  heated.  It 
reduces  the  salts  of  copper  on  prolonged  boiling  in  alkaline  solution. 
The  xanthine  bases  (p.  409)  and  uric  acid  are  pptd.  by  a  mixture  of 
equal  volumes  of  a  13  per  cent,  solution  of  CuSO  and  a  50:100  solu- 
tion of  NaHS03  (Krliger-Wolff  reagent),  which  does  not  ppt.  urea. 
Uric  acid  is  pptd.  from  solutions  containing  magnesia  mixture,  by 
ammoniacal  AgN03,  as  silver-magnesium  urate.  It  is  pptd.,  as  ammo- 
nium urate,  by  complete  saturation  of  its  solutions  with  NH4C1. 

Uric  acid  behaves  as  a  dibasic  acid.  The  monometallic  salts  are  formed 
by  dissolving  the  acid  in  solutions  of  the  metallic  carbonates,  or  by  treating 
solutions  of  the  dimetallic  salts  with  carbon  dioxide.  The  dimetallic  salts  are 
formed  by  dissolving  the  acid  in  solutions  of  the  metallic  hydroxides,  free  from 
carbonate.  Mono-ammonium  urate,  C5H3N403  ( NH4 ) ,  exists  in  the  solid  urines 
of  the  lower  animals,  and  in  urinary  sediments  and  calculi.  It  is  very  sparingly 
soluble  in  water.  Dipotassic  urate  is  alkaline  in  taste,  absorbs  C02  from  the 
air,  and  is  soluble  in  44  parts  of  cold  H2O.  Disodic  urate  forms  nodular 
masses,  soluble  in  77  parts  of  cold  water,  and  absorbs  CO2  from  the  air.  It  is 
probably  in  this  form  of  combination  that  uric  acid  exists  normally  in  the  urine. 
Monosodic  urate  is  much  less  soluble,  requiring  1,200  parts  of  water  for  its 
solution.  It  exists,  generally  amorphous,  in  urinary  sediments  (amorphous 
urates)  and  calculi,  and  in  the  arthritic  deposits  of  the  gouty,  sometimes  beauti- 
fully crystalline.  Monocalcic  urate,  soluble  in  603  parts  of  cold  water,  also 
occurs  occasionally  in  urinary  sediments  and  calculi,  and  in  "  chalk  stonrs." 
Monolithic  urate,  C5H8N4O8Li,  crystallizes  in  needles,  soluble  in  60  parts  of 
\\ater  at  50°,  or  in  368  parts  at  19°.  It  is  chiefly  with  a  view  to  the  formation 
of  this,  the  most  soluble  of  the  monometallic  urates,  that  the  salts  of  lithium 


SIX   MEMBERED   HETEROCYCLIC   RINGS 


409 


are  given  to  patients  suffering  from  the  uric  acid  diathesis.  Two  salts  of  uric 
acid  with  organic  bases  are  still  more  soluble.  Piperazine  urate  dissolves  in 
50  parts  of  water  at  17°  and  lysidine  urate  in  6  parts  of  water. 

The  Xanthine,  Alloxuric,  Purine,  or  Nuclein  Bases — form  a 
series  of  which  uric  acid  is  the  most  highly  oxidized  member,  and 
which,  like  uric  acid,  are  purine  derivatives: 


Uric  acid, 
Xanthine, 
Hypoxanthine, 
Guanine, 

Adenine, 

C5H4N403 
C5H4N4O2 
C5H4N40 
C5H5N50 

C5H5NB 

Heteroxanthine, 
Paraxanthine, 
Theobromine, 
Theophylline, 
Caffeine, 
Epiguanine, 

C5H8(CH8)N402 
C5H2(CH3)2N402 
C5H2(CH3)2N402 
C5H2(CH3)2N402 
C8H(CH3)3N402 
C5H4(CH3)N50 

Of  the  substances  named  in  the  first  column,  xanthine,  hypo- 
xanthine  and  guanine  are,  like  uric  acid,  ketopurines,  also  called 
oxypurines,  while  adenine  contains  no  oxygen;  and  guanine  and 
adenine  further  differ  from  xanthine  and  hypoxanthine,  in  that  they 
contain  an  amido  group.  Those  in  the  second  column  are  methyl 
derivatives  of  xanthine  or  of  guanine,  to  which  they  bear  the  same 
relation  that  the  methyluric  acids  do  to  uric  acid.  Besides  the  sub- 
stances above  enumerated,  carnine,  C7H8N403  and  episarkine, 
C4H603  ( ?)  probably  belong  in  this  class.  Adenine,  guanine, 
hypoxanthine  and  xanthine  are  products  of  decomposition  of  nucleic 
acids,  which  are  themselves  products  of  decomposition  of  nucleo- 
proteids.  The  relations  of  the  xanthine  bases  to  each  other  and  to 
uric  acid  are  shown  in  the  following  formulae: 


HN— CO 

OC     C.NH 

HN— C.NH  / 

Uric   acid. 
2,    6,    8-Triketopurine. 


\ 


C° 


HN— CO 
OC     C.NH 


Xantbine. 
2,  6-Diketopurine. 


H3C.N— CO 
OC     C.NH  ^ 

HN-iU// 

l-Methyl-2,  6- 
diketopurine. 


HN—  CO 

OC     C.N 


Heteroxanthine. 

7-Methyl  2,   6-diketo- 

purine. 


H3C.N— CO       CH3 

OC     C.N 


II 
—  C.N 


\ 


HN 

Paraxanthine. 

1,    7-Dimethyl- 

2,    6-diketopurine. 


HN— CO 

OC     C.N 


H,C 


\ 


J J.N  i 


CH3 
CH 


Theobromine. 

3,    7-Dimethyl- 

2,    6-diketopurine. 


H3C.N— CO 

OC     C.NH 

I     II 
H3C.N— C  .  N 


H3C.N— CO 

OC    C.N/ 


CH 


Theophylline. 

1,  3-Dimethyl- 

2,    6-diketopurine. 


\ 


H3C 


.N-H.N// 


CH 


Caffeine. 

1,  3,    7-Trimethyl- 

2,  6-diketopurine. 


HN—  CO 

I  I 

HC     C.NH 

II  II 

N—  C.N 


x 


CH 


Hypoxanthine. 
6-Ketopurine. 


HN—  CO 


.C 


H2N.C     C.NH 


CH 


Guanine. 
2-Amido-6-ketopurine. 


HN— CO 


H2N. 


N— C.N 


CH 


Epiguanine 

7-Methyl-2-amido- 

6-ketopurine. 


HC     C.NH 

N— C.N 


Adenine. 
6-Amidopurine. 


410  TEXT-BOOK   OF   CHEMISTRY 

Xanthine  —  Xanthic  Acid  —  Urous  Acid  —  2,  6-Diketopurine  —  2,  6- 
Dioxypurine  —  C5H4N402  —  occurs  in  a  rare  form  of  vesical  calculus, 
in  the  pancreas,  spleen,  liver,  thymus,  kidneys,  bijain,  and  in  the  melt 
of  fishes.  It  is  a  normal  constituent  of  the  urine  in  small  amount. 
Xanthine,  hypoxanthine,  guanine,  and  adenine  are  products  of  de- 
composition of  the  nucleins. 

Xanthine  is  obtained  synthetically,  either  by  the  deamidation  of 
guanine  by  nitrous  acid  (p.  412)  ;  or  by  Fischer's  method,  which,  in 
its  variations,  permits  of  the  formation  of  the  several  xanthine  bases 
from  uric  acid  through  the  chloropurines.  In  the  formation  of 
xanthine,  uric  acid  is  converted  into  2,  6,  8-trichloropurine  (1)  by 
POC13.  By  heating  with  excess  of  sodium  ethylate  this  is  converted 
into  2,  6-diethoxy-8-chloropurine  (2).  This  is  saponified  by  HC1  to 
2,  6-diketo-8-chloropurine  (3),  which  is  then  reduced  by  HI  to 
xanthine  (4) 

N-C.C1  N=C.OC2H3  HN—  CO  HN—  CO 

Cl.C     C.NHv  C2H5O.C     C.NHV  OC     C.NH  v  OC     C.NH^ 


(1)  (2)  (3)  (4) 

Xanthine  and  hypoxanthine  are  also  formed  in  small  amount  by 
the  direct  reduction  of  uric  acid  by  nascent  formic  acid.  By  methyla- 
tion  xanthine  yields  theobromine  and  caffeine. 

It  is  usually  amorphous,  but  may  form  crystalline  plates.  It  is 
very  sparingly  soluble  in  water,  1:14,500  at  16  degrees,  1:1,400  at 
100  degrees;  insoluble  in  alcohol  or  ether;  readily  soluble  in  alkalies. 
Its  ammoniacal  solution  gives  a  gelatinous  ppt.  with  AgN03.  If  dis- 
solved in  HN03,  and  the  solution  evaporated,  it  leaves  a  yellow 
residue  which,  with  NaOH,  turns  reddish-yellow,  then  purple-red 
(xanthine  reaction).  It  gives  the  Weidel  reaction  (p.  402).  As  this 
reaction  is  given  with  uracil,  cytosine,  uric  acid,  xanthine,  all  the 
methylxanthines,  and  alloxan,  but  not  by  hypoxanthine,  guanine,  or 
adenine,  it  would  seem  to  be  characteristic  of  those  pyrimidine  com- 
pounds which  contain  the  group  N.CO.N,  and  notably  of  those  con- 
taining two  ketone  groups,  although  cytosine  contains  but  one  such 
group. 

Methylxanthines.  —  1-Methylxanthine,  7-methylxanthine,  or  heteroxan- 
thine,  and  1,  7-dimcthylxanthine,  or  paraxanthine  occur  in  small  quantities  in 
the  urine.  With  the  xanthine  reaction  1-methylxanthine  gives  an  orange  color; 
the  others  are  negative.  Theobromine,  or  3,  7-dimethylxanthine,  occurs  in  the 
seeds  of  Theobroma  cacao  in  the  proportion  of  about  2  per  cent.  It  is  a  crystal- 
line powder,  bitter  in  taste;  difficultly  soluble  in  water,  alcohol,  ether  and  chloro- 
form ;  soluble  in  acids,  with  which  it  forms  salts  ;  soluble  in  NH4OH.  By  partial 
demethylation  it  yields  heteroxanthine.  With  AgN03  it  forms  a  crystalline  ppt., 
which,  heated  with  methyl  iodide,  yields  caffeine.  Theobromine  and  caffeine  have 
both  been  obtained  synthetically  by  methylation  of  xanthine,  formed  by  oxida- 
tion of  guanine  (p.  411).  Theophylline,  or  1,  3-dimethylxaiithine,  occurs  in 


Cl.C 


SIX   MEMBERED   HETEROCYCLIC   RINGS  411 

tea  extract.  It  is  formed  from  1,  3-dimethyluric  acid,  and  is  manufactured  for 
use  as  a  diuretic,  from  uric  acid.  Caffeine,  or  theine,  or  guaranine,  or  1,  3,  7- 
trimethylxanthine,  exists  in  coffee,  tea,  Paraguay  tea,  guarana  and  other  plants, 
and  may  be  produced  from  1,  3,  7-trimethyluric  acid.  It  crystallizes  in  long, 
silky  needles;  faintly  bitter;  soluble  in  75  parts  of  water  at  15  degrees;  less 
soluble  in  alcohol  and  ether.  With  HN03,  evaporation,  and  addition  of  NH4OH 
it  gives  a  purple  color. 

Hypoxanthine  —  Sarkine  —  6-  Ketopurine  —  6-Oxypurine  —  C5H4N40 
•occurs  as  a  constituent  of  the  nucleins  in  the  same  situations  as 
xanthine  ;  also  in  notable  amount  in  the  blood  of  leukemia,  and  in  the 
melt  of  salmon  and  carp  ;  also  in  numerous  seeds  and  pollen  of  plants. 
It  is  a  product  of  the  decomposition  of  nucleins  by  acids,  by  peptic 
and  tryptic  digestion,  and  by  putrefaction. 

Hypoxanthine  is  obtained  synthetically,  either  by  deamidation  of 
adenine  by  nitrous  acid  (adenine,  p.  412)  ;  or  by  Fischer's  method 
from  uric  acid  through  2,  6,  8-trichloropurine  (xanthine,  p.  410), 
(1).  This  is  converted  into  2,  8-dichloro-6-ketopurine  (2)  by  KOH; 
and  this  is  reduced  by  HI  and  PH4I  to  hypoxanthine  (3)  : 
N=C.C1  HN—  CO  HN—  CO 

C.NH  Cl.C    C.NH.  H.C     C.NH 

||        \C.C1  II      II     T//C-C1  ||      ||        >CH 

N  "  N—  C  .  N  '  N—  C  .  N  " 

(1)  (2)  (3) 

It  crystallizes  in  small,  colorless  needles  ;  soluble  in  300  parts  of 
cold  water,  or  in  75  parts  of  boiling  water;  soluble  in  acids  and  in 
alkalies.  Its  ammoniacal  solution  forms  a  ppt.  with  AgN03.  Fum- 
ing HN03  oxidizes  it  to  nitroxanthine.  It  does  not  give  the  Weidel 
reaction.  When  acted  upon  by  zinc  and  HC1,  and  then  treated  with 
excess  of  alkali,  it  forms  a  ruby-red  solution,  which  turns  brown-red 
(Kossel's  reaction). 

Guanine  —  2-Amido-6-ketopurine  —  occurs  abundantly  in  guano, 
and  as  the  principal  constituent  of  the  excrement  of  spiders;  in  less 
amount,  as  a  constituent  of  guanylnucleic  acid,  in  the  spleen,  liver, 
pancreas,  in  the  melt  of  the  salmon,  in  the  scales  and  swimming 
bladders  of  certain  fishes,  in  normal  urine  in  traces,  in  the  blood  in 
leukemia  ;  and  in  the  young  leaves  and  pollen  of  certain  plants. 

Guanine  is  produced  synthetically  in  two  ways:  By  Fischer's 
method,  proceeding  as  in  the  synthesis  of  hypoxanthine  (above)  to 
the  formation  of  2,  8-dichloro-6-ketopurine  (1).  This  is  converted 
by  heating  with  alcoholic  ammonia  at  150°  into  2-amido-8-chloro-6- 
ketopurine  (2)  ;  which  is  reduced  by  HI  to  guanine: 

HN—  CO  HN—  CO  HN—  CO 

Cl.C     C.NH.  H2N.C     C.NH.  H2N.C     C.NHV 

' 


(1)  (2)  (3) 


412  TEXT-BOOK   OF   CHEMISTRY 

By  Traube's  synthesis,  starting  from  cyanoacetic  ester  (4)  and 
guanidine  (5),  which  condense  to  cyanoacetic  guanide  (6).  This,  by 
union  of  the  amide  and  cyanogen  groups,  forms  an  amidine,  and  the 
six-membered  ring  closes  to  2,  4-diamido-6-oxypyrimidine  (7).  This, 
by  addition  of  NaN02  to  solution  of  the  base,  forms  a  rose-colored 
isonitroso  compound,  neither  basic  nor  acid,  which  on  reduction  by 
H2S  forms  2,  4,  5-triamido-6-oxypyrimidine  (8),  which  is  a  strong 
diacid  base,  and  which,  on  boiling  with  strong  formic  acid,  forms 
guanine  (9)  : 

HN  COO(C2H8)  HN— CO  N=C.OH 

H2N.c  CH2  H2N.i   ina  H2N.i   in 

H2N  CN  HN     CN  N— C.NH2 

(5)  (4)  (6)  (7) 

N=C.OH  HN— CO  HN— CO 

H2N.C     C.NH2  H2N.C     C.NHV  OC     C.NH . 

II     II        //CH  ;>CH 

1^-i.NH,  N1— t.N  //  HK— C.N   // 

(8)  (9)  (10) 

Guanine  is  deamidated  by  nitrous  acid  with  formation  of  xanthine 
(10): 

HN.CO.C.NH  v  HN.CO.C.NH . 

I         M        \CH+HNO,=      I  \CH-f  N2+H20; 

H2N.C:N-C  .  N//  OC.NH.C  .  N  // 

and  xanthine,  in  turn,  may  be  methylated  to  theobromine  and  caffeine. 
Guanine  is  oxidized  by  KMn04+HCl,  with  formation  of  guanidine 
and  oxalylurea: 

HN .  CO.C.NH  v  H2N  CO.NH  v 

|          1 1         >,CH+30+H2O=  +      I  /)  C04-C02. 

H2N.C:N— C.N    //  H2N.C:NH  CO.NH  7/ 

Guanine  is  a  white  or  yellowish,  amorphous  and  odorless  powder : 
almost  insoluble  in  water,  alcohol  and  ether;  readily  soluble  in  acids 
and  alkalies.  It  forms  crystalline  ppts.  with  silver  nitrate  and  with 
picric  acid.  It  gives  the  xanthine  reaction  with  HN03  and  NaOH; 
but  it  does  not  respond  to  the  Weidel  reaction. 

Adenine — 6-Amidopurine — C5H,N5  —  exists,  in  nucleic  acids, 
widely  disseminated  in  nucleated  cells,  most  abundantly  in  carp-melt 
and  in  the  thymus  gland.  It  occurs  in  the  blood  and  urine  in 
leukemia,  and  also  exists  in  yeast  and  abundantly  in  tea  leaves. 

It  is  formed  synthetically  by  Fischer's  method:  By  the  action  of 
POC13  upon  potassium  urate  2,  6-dichloro-8-ketopurine  (1)  is  pro- 
duced. This  is  converted  into  2-chloro-6-amido-8-ketopurine  (2)  by 


SIX   MEMBERED   HETEROCYCLIC   RINGS  413 

NH3.     This  is  converted  by  POC13  into  2,  8-dichloro-6-amidopurine 
(3)  ;  which  is  reduced  by  HI  to  adenine  (4)  : 

N=C.NH2 


Cl.C     C.NHX  Cl.C     C.NHX  Cl.C     C.NHX  HC     C.NH  v 

)CO            ||     ||          >CO             ||     ||        \CC1  |J     ||         /)CH 

N—  C.NH  /                 N—  C.NH  '                    N—  C  .  N  7/  N—  C  .  N  " 

(1)                                    (2)                                  (3)  (4) 

As  guanine  is  deamidated  to  xanthine,  so  adenine,  on  deamidation, 
yields  hypoxanthine  : 

N  :  C  (  NH2  )  .C.NH  x  HN.CO.C.NH  x 

I  M         /)CH+HN02=    I  ||        /)CH+N2-fH20. 

CH:N  --  C.N"  CHrN.C.N// 

Adenine  crystallizes  in  nacreous  plates,  or  in  long  needles,  with 
3  Aq,  which  they  lose  at  100  °,  although  they  suddenly  become  opaque 
at  53°,  a  property  characteristic  of  adenine.  Very  soluble  in  hot 
water,  it  requires  1,086  parts  of  cold  water  for  its  solution  ;  insoluble 
in  cold  alcohol,  ether  and  chloroform;  readily  soluble  in  acids  and 
alkalies,  with  which  it  forms  compounds.  Its  solubility  in  ammonia 
is  less  than  that  of  hypoxanthine,  but  greater  than  that  of  guanine. 
It  forms  crystalline,  difficultly  soluble  compounds  with  silver  nitrate 
and  with  picric  acid.  It  is  not  reddened  by  warming  with  HN03i 
and  moistening  the  residue  with  alkali;  does  not  respond  to  the 
Weidel  reaction,  but  behaves  like  hypoxanthine  towards  Kossel's 
reaction. 

Carnine  —  C7H8N4O3  —  is  obtained  from  Liebig's  meat  extract,  and  has  also 
been  found  in  the  muscular  tissues  of  fishes  and  frogs,  and  in  the  urine.  It  is 
isomeric  with  the  dimethyluric  acids.  It  forms  chalky,  microscopic  crystals, 
readily  soluble  in  hot  water,  sparingly  soluble  in  cold  water,  insoluble  in 
alcohol  and  ether.  It  forms  compounds  with  acids  and  with  alkalies,  similar 
to  those  of  hypoxanthine.  Chlorine,  bromine  and  nitrous  acid  convert  it 
into  hypoxanthine,  with  elimination  of  the  elements  of  acetic  acid.  It  does  nofc 
respond  to  the  Weidel  reaction. 

Epiguanine  —  C6H7N5O3.  —  Besides  7-methylxanthine,  which  is  heteroxanthine, 
and  7-methyluric  acid,  similar  derivatives  of  hypoxanthine,  guanine  and  adenine 
have  also  been  obtained  synthetically.  7-Methyl-guanine  is  epiguanine,  which 
occurs  in  minute  quantity  in  the  urine.  Episarkine  is  possibly  identical  with 
epiguanine. 

Triazines  —  are  compounds  containing  three  nitrogen  atoms  in  a 
six-membered  ring: 

H 
C 

N=CH  N=CH  N=CH 

|]  II 

or          N     CH  N     CH 


HC        N 

or 


N 

1,  2,  3-Triazino.  1,    2,    4-Triazlne.  1,    3,    5-Triazine. 

Orthotriazine.  Metatriazlne.  Paratrlazine. 

Cyanidine. 


414 


TEXT-BOOK    OF    CHEMISTRY 


The  parent  ortho-  and  meta-compounds  are  not  known,  but  many 
of  their  derivatives  have  been  obtained,  none  of  which  is,  however,  of 
medical  interest. 

Para-,  or  /-triazine,  also  called  cyanidine,  is  the  still  unidentified 
trihydrocyanic  acid,  which  is  the  parent  substance  of  certain  metal- 
locyanides,  and  of  the  cyanuric  compounds  (p.  307). 

B.  CONDENSED  HETEROCYCLIC  COMPOUNDS. 

These  compounds,  which  are  more  numerous  than  the  correspond- 
ing carbocyclic  compounds,  may  be  considered  as  being  derived  from 
the  latter  by  substitution  of  N  for  methine,  =CH — ,  or  of  0,  S,  or 
NH  in  a  bivalent  position,  or,  as  in  the  case  of  iso-indole  (below), 
by  substitution  and  modification  of  internal  linkage.  The  number 
of  these  substances  is  still  further  increased  by  the  existence  of  four 
ringed-compounds,  such  as  the  anthraquinolines  and  indigo-blue 
(p.  417).  The  formulae  below  are  those  of  some  of  the  nitrogen 
derivatives,  in  which  indole  and  isoindole  may  be  considered  as  de- 
rived from  indene  (p.  385)  :  carbazole  from  fluorene;  quinoline,  iso- 
quinoline  and  naphthydrine  from  naphthalene:  acridine  and  the 
anthrapyridines  from  anthracene;  and  phenanthridine  from  phen- 
anthrene : 


H 
C 

//4\ 
HC3         C CH/3 

HC2         C  CHa 

\\1/    \   / 
C  Nn 

H         H 

Benzo-pyrrole. 
(Indole). 

H          H 

C  C7 

//4\    /    \\ 
HC3         C  CH/3 

HC2         C  CHa 

\\1/    \    // 
C          N 
H 


Benzo-pyridine. 
(Quinoline) 

H         H         H 

C 

C          C 

II  ^ 

/ 

\     /    \\ 

HC 

"c 

C 

H(l 

I! 

fl 

\\  / 

'  \ 

/    \    // 

C 

N         C 

H 

H 

Acridine. 

H  H 

C  C 

//   \  /   \\ 

HC  C C  CH 

Hrf"1  C*  ^"ITT 

\J  \J  \J  V^il 

\\    /    \    /    \    // 
C          N          C 
H          H         H 

Diphenylone-imide. 
(Carbazole). 


H 
C 

\ 


\\ 


HC  C  CH 

HC  C  CH 


\\ 


\ 


N 


N 


CH 


HC 


H         ] 
C         ( 

//  \    / 
C 

II 

a 

^ 

\     / 

c 

H 

H 
C 

'   \\ 

c 

\\  /  \ 

C         ( 
H         1 

(J 

/     \ 

j 

BE 

^C 
H 

a-.  \iithnipyrldine. 

Naphthydrine. 


CH 


CONDENSED   NUCLEI   CONTAINING   A   NITROGEN   MEMBER  415 

H         H         H  H    H  H    H 

C.        C  C  C=C  C=C 

//\/\/\\  /          \          /          \ 

HC         C          C          CH  HC  C— C  CH 

II        N         I  \\        //        \\        // 

C          C          CH  C— C  C— C 

\\  /    \\/    \   //  H       \          /       H 

C         C         N  N=C 

H          H  H 

/3-Anthrapyridine.  Phenanthridine. 


CONDENSED  NUCLEI  CONTAINING  A  NITROGEN  MEMBER. 
BENZOPYRROLE    AND    ITS    DERIVATIVES—  INDIGO    COMPOUNDS 

Indole  —  Benzopyrrole  —  (formula  p.  414)  —  is  produced:  (1)  by 
distilling  oxindole  oxer  zinc-dust;  (2)  by  heating  o-nitric  cinnamic 
acid  with  potash  and  iron  filings,  or  by  similar  reduction  of  other 
unsaturated  o-nitro  substitution  products  of  benzene  (3)  by  the 
interaction  of  calcium  formate  and  phenylglycocoll  (p.  375).  It  is 
one  of  the  products  of  putrefaction  of  the  proteins  by  anerobic 
bacteria,  and  is  formed  in  the  intestine  during  pancreatic  digestion 
of  those  substances.  It  is  partly  eliminated  with  the  feces  and 
partly  reabsorbed,  appearing  in  the  urine  in  sulphocon  jugate  com- 
bination. It  crystallizes  in  large,  shining,  colorless  plates,  having 
the  disagreeable  odor  of  naphthylamine.  It  is  a  weak  base,  and  its 
salts  are  decomposed  by  boiling  water.  Its  aqueous  solution,  acidu- 
lated with  HC1,  is  colored  rose-red  by  KN02.  By  fusion  with  KOH 
it  yields  aniline.  It  gives  the  "  pine-shaving  reaction  "  (p.  416).  It 
forms  a  compound,  crystallizing  in  red  needles,  with  picric  acid. 

Indole  Homologues  —  Derivatives  of  indole  are  produced  by  sub- 
stitution either  in  the  benzene  or  in  the  pyrrole  ring.  The  positions 
are  distinguished  as  Bz.  1,  2,  3,  4  and  Py.n,  a,  and  /?  (see  formula 
p.  414).  The  alkyl  indoles,  the  superior  homologues  of  indole,  are 
formed:  (1)  by  heating  aniline  with  compounds  containing  the  group 
CO.CH2C1.  Thus  chloracetone  and  aniline  yield  tf-methylindole  : 

CH2C1.CO.CH3+C6H5.NH2=C6H4(™X)C.CH3  +HC1+H20  ; 

(2)  By  heating  the  phenylhydrazones  of  the  ketones,  aldehydes  or 
ketone  acids  with  ZnCl2.  Thus  n,  <*-dimethylindole  is  obtained  from 
acetone-phenyl-methyl-hydrazone: 


The  best  known  alkyl  indoles  are  those  in  which  the  alkyl  group 
is  in  the  pyrrole  ring.  They  dissolve  in  concentrated  acids,  and  are 
precipitated  unaltered  from  the  solutions  by  dilution  with  water. 
Fused  with  KOH,  they  yield  potassium  salts  of  indole-carboxylic 
acids.  Their  hydrogen  may  be  replaced  by  acidyls  or  by  the  diazo 


416  TEXT-BOOK   OF   CHEMISTRY 

group.      They    give   the    "pine-shaving    reaction,"    and    form    red, 
crystalline  compounds  with  picric  acid. 

Indole-/2-acetic  acid. — The  product  of  putrefaction,  which  also 
exists  in  normal  urine,  described  as  skatole  carboxylic  acid,  is  not 
that  substance,  but  its  isomere,  indole- /^-acetic  acid  (formula  below). 
It  produces  an  intense  violet  color  with  HC1  and  dilute  FeCl3  solution. 

Tryptophane — Proteinochromogen — /?./?.-Indole-<*.-amidopropionic 
Acid— 

CH2 

! 

.CH2.COOH  HC        C C CH.NH2 

COOH 


is  a  product  of  decomposition  of  proteins  by  energetic  decomposing 
agents  such  as  Ba(OH)2,H2S04,  tryptic  digestion  and  putrefaction, 
but  not  by  peptic  digestion.  With  Br  or  Cl  it  forms  a  red-violet  pig- 
ment, called  proteinochrome.  It  crystallizes  in  shining  plates,  easily 
soluble  in  hot  water,  difficultly,  in  cold  water  or  alcohol.  When  heated 
it  yields  indole  and  skatole.  It  gives  the  Adamkiewicz  reaction.  Its 
solution  on  a  pine  shaving,  previously  moistened  with  HC1,  and  sub- 
sequently washed  and  dried,  gives  a  purple  color  (pyrrole  reaction). 
By  anerobic  putrefaction  it  yields  indole-  yfl-propionic  acid;  and  by 
aerobic  putrefaction  indole-  y#-acetic  acid,  and  indole. 

^-Methyl-indole—  Skatole—  CCH4(^H3)^CH—  exists  in  feces, 
in  which  it  exceeds  the  indole  in  amount.  It  is  formed  during  putre- 
faction of  the  proteins,  or  by  the  action  upon  them  of  KOH  in 
fusion;  also  by  the  reduction  of  indigo.  It  is  best  obtained  syntheti- 
cally by  heating  propidene-phenylhydrazone  with  zine  chloride: 


It  crystallizes  in  brilliant  plates;  f.  p.  95°;  insoluble  in  water, 
soluble  in  alcohol  and  in  ether;  distils  with  vapor  of  water;  has  a 
strong  fecal  odor.  Its  solution  in  concentrated  HC1  is  violet.  Its 
H2S04  solution  is  colored  deep  purple  when  heated.  Skatole,  like 
indole,  is  in  part  reabsorbed  from  the  intestine,  and  appears  in  the 
urine,  combined  with  sulphuric  and  glucuronic  acids. 

Iso-indole  —  (formula,  p.  414)  —  is  formed  by  the  action  of  alco- 
holic ammonia  upon  brom-acetophenone.  It  crystallizes  in  colorlrss, 
silky  plates;  f.  p.  195°;  insoluble  in  water,  soluble  in  alcohol,  ether 
and  benzene. 

Indoxyl—  ^.Oxyindole  —  C6H4H°3CH  —  not    to    be    con- 


CONDENSED   NUCLEI   CONTAINING  A  NITROGEN   MEMBER  417 

founded  with  oxindole  (below),  is  a  phenolic  derivative  of  indole, 
obtained  from  indigo-blue  by  fusion  with  KOH  without  contact  of 
air;  or  from  its  a-carboxylic  acid,  indoxylic  acid.  It  is  a  very 
unstable,  oily  substance,  soluble  in  water,  and  readily  oxidized  to 
indigo-blue  (below).  It  readily  combines  with  sulphuric  acid  or  the 
sulphates  to  form  indoxyl-sulphuric  acid,  the  potassium  salt  of  which 
is  uroxanthine,  or  urinary  indican.  This  latter  is  formed  from  indole, 
and  its  relations  are  shown  by  the  following  formula: 

CH3  Ovx     /OH 

I  S 

CH2.OH  O//    XO.CH2.CH3 

Ethyl-alcohol.  Ethyl-sulphuric  acid. 

O       /OH 
\\g/ 

O//   XO.C6HS 

Phenyl-sulphuric 
acid. 

0  OH 

\\    / 
S  NH 

//    \       /       \ 
O  O.C=:CH— C6H4 

Indoxyl-sulphuric   acid. 

Acids  decompose  it,  with  formation  of  indoxyl,  which  is  converted 
into  indigo-blue  by  FeCl3. 

Oxindole — C6H4<^N£2/CO — the  lactam  of  o-amido-phenyl  acetic 
acid,  is  obtained  from  dioxindole  by  reduction  with  sodium  amalgam 
in  acid  solution;  or  by  reduction  of  o-nitrophenyl-acetic  acid.  It 
crystallizes  in  easily  soluble,  colorless  needles;  f.  p.  120°.  In  moist 
air  it  oxidizes  to  dioxindole.  It  reduces  ammoniacal  silver  nitrate 
solution.  It  combines  with  acids  and  bases. 

Isatine  C6H4<^NH/CO  —  the  lactam  of  o-amido-benzoyl-formic 
acid,  is  formed  by  oxidation  of  indigo-blue  by  HN03 ;  by  oxidation 
of  oxindole ;  and  by  other  methods.  It  crystallizes  in  shining,  trans- 
parent, red-brown  prisms,  odorless,  sparingly  soluble  in  water, 
readily  soluble  in  alcohol. 

Indigo-blue— Indigotine—C6H4^gV),C:C^^>C6H4— constitutes 
the  greater  part  of  commercial  indigo.  It  does  not  exist  preformed 
in  nature,  but  many  plants,  particularly  Indigotifera  tinctoria  and 
I  satis  tinctoria,  contain  a  yellow  glucoside,  indican  (p.  363),  which 
on  heating  with  dilute  acids,  or  probably  by  enzymic  action  on  ex- 
posure to  air  in  presence  of  water,  is  decomposed  into  a  sugar  and 
indigo-blue.  Commercial  indigo  contains  20  to  90  per  cent,  of 


418  TEXT-BOOK   OF   CHEMISTRY 

indigo-blue,  which  may  be  separated,  nearly  pure,  by  cautious  sub- 
limation. It  is  formed  in  several  reactions,  e.g.,  by  oxidation  of 
indoxyl  by  FeCl3  and  HC1  ;  from  o-nitro-cinnamic  acid  by  two 
methods;  by  fusing  phenyl-glycocoll  with  KOH  ;  or  by  heating 
o-nitro-acetophenone  with  zinc  dust.  It  forms  purple-red,  metallic 
shining  prisms  or  plates,  odorless,  tasteless,  neutral,  soluble  in  hot 
aniline,  hot  oil  of  turpentine,  and  melted  paraffin,  insoluble  in  the 
usual  solvents.  When  heated  it  is  in  part  converted  into  a  dark-red 
vapor,  and  partly  decomposed  into  aniline  and  other  products.  In 
the  presence  of  aqueous  alkaline  solutions,  reducing  agents  convert 

indigo-blue    into    indigo-  white,    or    di-indoxyl,C6H4yNjj^JJ^C  —  C- 

^-LNH/  C6H4,  which  dissolves  in  the  alkali.  This  substance  absorbs 
oxygen  from  the  air  rapidly,  with  regeneration  of  indigo-blue.  In 
absence  of  air  it  may  be  precipitated  from  its  alkaline  solution  by 
HC1,  as  a  white,  crystalline  powder,  insoluble  in  water,  but  soluble 
in  alcohol  and  ether,  forming  yellow  solutions.  When  oxidized,  as 
by  warming  with  dilute  HN03,  indigo-blue  is  converted  into  isatine, 
whose  dilute  solutions  are  also  yellow.  Hence  the  decoloration  of 
indigo-blue  solution  is  utilized  as  a  test  both  for  oxidizing  (HN03) 
and  for  reducing  (Mulder-Neubauer  test  for  glucose)  substances. 

QUINOLINE  AND   ISO-QUINQLINE   AND   THEIR   DERIVATIVES. 

The  quinoline,  or  benzo-pyridine  bases  accompany  the  pyridine 
bases  in  bone-oil,  and  like  those  substances,  are  closely  related  to  the 
vegetable  alkaloids.  Quinoline,  the  parent  substance  of  the  group, 
was  first  obtained  by  distilling  quinine  and  cinchonine  with  lime. 

Chemically  the  quinolines  are  also  related  to  the  naphthalenes, 
and  are  formed  by  similar  synthetic  methods.  Thus  quinoline  is 
formed  from  allyl-aniline  : 

C6H5.NH.CH2.CH  :CH2=C6H4CH:'CH  +2H2, 


in  the  same  manner  as  naphthalene  is  formed  from  phenyl- 
butylene.  Quinoline  and  its  derivatives  may  also  be  produced  syn- 
thetically: (1)  From  o-amido-benzenic  compounds  containing  an 
oxygen  atom  in  the  second  lateral  chain.  Thus  o-amido-benzoic  alde- 
hyde and  acetone  yield  tf-methyl-quinoline  : 

/  CHlCH 

+2H20. 


(2)  By  heating  the  anilines  with  glycerol  and  H2S04,  in  presence 
of  an  oxidizing  agent,  such  as  nitro-benzene  : 

/CH:CH 

C6H5.NH2+CH2OH.CHOH.CH2OH=C6H4  I    +3H20+H2 


ALKALOIDS  419 

(3)  By  the  action  of  aldehydes  upon  anilines  in  presence  of 
H2S04  or  HC1.  Thus  <*-methyl-quinoline  is  obtained  from  aniline  and 
acetic  aldehyde : 

/CH:CH 
C6H5.NH2+2CHO.CH3=C6H4  |  +2H20+H2 

\N    :C(CH3) 

The  quinoline  bases  are  liquids  of  penetrating  odor,  sparingly  sol- 
uble in  water,  readily  soluble  in  alcohol  and  in  ether.  They  are 
strong  triacid  bases,  and  form  salts  and  ammonium-like  compounds. 

/CH:CH 

Quinoline — C6H4  I     —is  a  mobile  liquid;  b.  p.  238°,  becom- 

\N    :  CH 

ing  rapidly  brown  on  exposure  to  air;  has  an  intensely  acrid  and 
bitter  taste,  and  an  odor  somewhat  like  that  of  bitter  almonds; 
sparingly  soluble  in  water,  readily  soluble  in  alcohol  and  ether.  Its 
dichromate  crystallizes  in  yellow  needles;  f.  p.  165°;  very  sparingly 
soluble  in  water. 

Quinoline  is  of  medical  interest  chiefly  in  connection  with  the 
vegetable  alkaloids  of  which  it  is  the  nucleus  (p.  428).  Certain  syn- 
thetic basic  substances  containing  the  quinoline  nucleus  have  also 
been  used  in  medicine,  in  saline  combination,  as  antiperiodics  and 
antipyretics. 

yCH.CH 

Iso-quinoline — C6H4/         |  — differs  from  quinoline  in  that  the 

attachment  of  the  benzene  and  the  pyridine  rings  is  by  the  ft  and  y 
positions  of  the  latter  in  iso-quinoline,  and  by  the  a  and  ft  positions 
in  quinoline  (see  formulae,  p.  414).  It  accompanies  quinoline  in  coal- 
tar,  and  is  the  nucleus  of  some  of  the  opium  alkaloids  (p.  437).  It 
resembles  quinoline  in  its  properties.  F.  p.  23°;  b.  p.  240.5°. 

ALKALOIDS. 

Until  the  constitution  of  all  the  substances  grouped  under  this 
term  shall  have  been  determined,  the  limitations  of  the  application  of 
the  name  can  be  only  provisional.  It  was  first  applied  to  the  few 
alkali-like  substances  first  obtained  from  vegetable  products,  the 
vegetable  bases  morphine,  narcotine,  veratrine,  strychnine.  After- 
wards its  application  was  extended,  and  at  the  same  time  made  more 
precise,  to  include  organic,  nitrogenized  substances,  alkaline  in  re- 
action, and  capable  of  combining  with  acids  to  form  salts  in  the  same 
way  as  does  ammonia.  This  limitation,  is,  however,  too  broad,  as  it 
classes  the  aliphatic  amines,  and  other  similar  bodies,  with  the  true 
alkaloids,  which  are  cyclic.  All  substances  generally  classed  as  alka- 
loids, whose  constitution  has  been  determined,  contain  at  least  one 
nitrogen-containing  heterocyclic  ring,  except  theobromine  and  caf- 
feine, which  are  not  true  alkaloids,  but  purine  bases  (p.  409).  Almost 
all  alkaloids  of  known  constitution  contain  the  pyridine  ring,  more 


420  TEXT-BOOK   OF   CHEMISTRY 

or  less  modified  by  hydrogcnation,  either  alone  or  in  quinoline  or 
isoquinoline.  Therefore,  until  recently,  alkaloids  were  considered  to 
be  :  basic  substances  containing  the  pyridine  ring.  But  the  hygrines, 
alkaloids  existing  in  coca  leaves,  are  derivatives,  not  of  pyridine,  but 
of  pyrrolidine,  a  five-membered  nucleus.  So  far  as  is  now  known, 
no  alkaloid  contains  more  than  one  nitrogen  atom  in  one  and  the 
same  ring.  Therefore,  provisionally,  it  may  be  stated  that  the  alka- 
loids are  basic  substances  derived  from  heterocyclic  nuclei  containing 
but  one  nitrogen  atom  in  any  nucleus.  Under  this  definition  pyri- 
dine and  quinoline  and  their  homologues  are  alkaloids,  as  well  as 
indole,  and  other  basic  pyrrole  compounds. 

Properties.  —  Some  of  the  alkaloids,  nicotine,  coniine,  sparte'ine 
and  arecoline  are  liquid,  volatile,  and  contain  C,  N  and  H.  Most  of 
them,  to  the  number  of  more  than  a  hundred,  are  solid,  crystalline, 
only  partially  volatile  without  decomposition,  if  at  all,  and  contain 
C,  N,  H  and  0.  Most  of  the  alkaloids  are  very  sparingly  soluble  in 
water,  although  some  are  readily  soluble;  but  soluble  in  alcohol, 
ether,  petroleum-ether,  chloroform,  benzene  or  amylic  alcohol.  Their 
salts,  on  the  other  hand,  are,  for  the  most  part,  soluble  in  water, 
but  insoluble  in  the  other  solvents  mentioned,  except  alcohol,  in  which 
they  are  soluble.  They  are  laevogyrous,  except  quinidine,  chincho- 
nine,  coniine,  narcotine,  and  pilocarpine,  which  are  dextrogyrous. 
Usually  their  rotary  power  is  diminished  by  combination  with  acids, 
although  with  quinine  the  reverse  is  the  case.  Free  narcotine  is 
laevogyrous,  its  salts  are  dextrogyrous.  Most  of  the  alkaloids  are 
bitter  in  taste,  and  alkaline  in  reaction. 

The  naming  of  the  salts  of  the  alkaloids  has  been  the  subject  of  no  little 
discussion.  The  names  of  the  alkaloids  are  made  to  terminate  in  ine.  As 
most  of  the  alkaloids  are  tertiary  amines  and  some  secondary  amines,  they 
combine  with  acids  in  the  same  manner  that  ammonia  does,  that  is,  without 
elimination  of  water  or  of  hydrogen,  and  by  change  of  the  nitrogen  valence  from 
trivalent  to  quinquivalent: 

2H,:     +     H2S04     =      (Ha.:N:)a((f54 
Ammonfa.       Sulphuric   acid.       Ammonium  sulphate. 


2  [  (  C1TH1U08  )  :N  ]  +  H2S04  =  [  (  Clf  H^O.  )  ;N  :  j  2 

Morphta.  Sulphuric   acid.          Morphi'tm   sulphate. 

Therefore  these  salts  do  not  contain  morphine,  CMHuOaN'",  as  a  substitute 
for  the  hydrogen  of  the  acid,  but  the  hypothetical  morphium  (  Ca7H2003NT  )  ',  as 
the  ammoniacal  salts  are  not  salts  of  ammonia,  NH3,  but  of  ammonium,  NH4. 
The  compounds  formed  by  the  union  of  morphine  and  other  alkaloids  with  the 
hydracids,  HC1,  HBr,  HI,  may  properly  and  conveniently  be  referred  to  as 
morphine  hydrochloride  (not  hydrochlorate  )  hydrobromide,  hydroiodide,  etc.,  they 
being  considered,  not  as  salts  of  those  acids,  but  as  compounds  in  which  one 
of  the  valences  of  the  quinquivalent  nitrogen  atom  is  satisfied  by  hydrogen  and 
another  by  chlorine. 


ALKALOIDS  421 

Many  of  the  alkaloids  behave  like  esters,  and  are  hydrolyzed  by 
baryta  or  the  caustic  alkalies,  or  by  mineral  acids,  into  two  com- 
ponents, one  a  base,  the  other  an  acid,  the  latter  usually  cyclic  and 
nitrogenous.  On  the  other  hand,  concentrated  HC1  removes  H20 
from  those  alkaloids  containing  more  than  one  hydroxyl,  converting 
them  into  apo-alkaloids,  as  morphine  is  converted  into  apomorphine. 
Other  alkaloids,  containing  methoxyl  groups  (OCH3)?  when  acted 
upon  by  concentrated  HC1,  are  modified  by  replacement  of  OH  for 
the  methoxyl  groups.  Reducing  agents  with  alkaloids  whose  nuclei 
contain  double  bonds,  form  hydro-bases,  as  piperidine  is  derived  from 
pyridine.  Distillation  with  zinc-dust  causes  removal  of  the  lateral 
chains  from  the  oxygen-containing  alkaloids,  with  liberation  of  pyri- 
drine  or  quinoline.  Oxidizing  agents  form  carboxylic  acids,  or  de- 
compose the  alkaloid  into  an  acid  and  a  base,  or  cause  the  union  of 
two  molecules  of  the  alkaloid  with  loss  of  hydrogen. 

General  Reactions  of  the  Alkaloids. — A  great  number  of  "gen- 
eral reagents"  for  alkaloids  have  been  suggested,  of  which  only  the 
more  important  can  be  here  mentioned: 

Potash,  soda,  ammonia,  lime,  baryta  and  magnesia  precipitate  the 
alkaloids  from  solutions  of  their  salts. 

Phospliomolybdic  acid  forms  a  precipitate  which  is  bright-yellow 
with  aniline,  morphine,  veratrine,  aconitine,  emetine,  atropine,  hyos- 
cyamine,  theme,  theobromine,  conime,  and  nicotine;  brownish-yellow 
with  narcotine,  codeine,  and  piperine;  yellowish-white  with  quinine, 
cinchonine,  and  strychnine;  yolk-yellow  with  brucine  (DeVry's,  or 
Sonnenschein  's  reagent) . 

Potassium  iodhydrargyrate  gives  a  yellowish  precipitate  with 
alkaloidal  solutions  which  are  acid,  neutral  or  faintly  alkaline  in 
reaction  (Mayer's  reagent). 

Classification  of  the  Alkaloids. — The  alkaloids  of  known,  or  par- 
tially known  constitution,  can  be  classified  according  to  the  nuclei 
which  they  contain: 

A.  Pyrrolidine- Alkaloids. — Tho  hygrines. 

B.  Pyridine- Alkaloids. — Trigonelline,  pilocarpine  (?). 

C.  Piperide'ine   (tetrahydropyridine)   Alkaloids. — Arecoline,  are- 
caidine  x-conicei'ne  (?),  pseudopelletierine,  pelletierine  (?). 

D.  Piperidine    Alkaloids. — Conime,    conhydrine,    arecaine,    juva- 
cine,  piperine. 

E.  Pyrrolidine-pyridine  AZ&aZowZs.— Nicotine. 

F.  Pyrrolidine-piperidine    Alkaloids. — Tropan    Alkaloids. — Atro- 
pine, hyoscyamine,  hyoscine  (?),  ecgonine,  cocaine,  cinnamyl-cocaine, 
tf-truxilline,  y^-truxilline,  benzoyl-ecgonine,  tropacocai'ne. 

G.  Quinoline    Alkaloids. — Cinchona    alkaloids,    strychnos    alka- 
loids (?). 

H.  Isoquinoline  Alkaloids. — Papaverine,  narcotine,  narceine  (°0, 
hydrastine,  berberine  (?). 


422  TEXT-BOOK   OF   CHEMISTRY 

I.   PJienanthrene  Alkaloids. — Morphine,  codeine,  thebai'ne. 

X.  Alkaloids  of  unknown  constitution. 

Piperidine  Alkaloids. — The  alkaloids  known  to  contain  a  single 
piperidine  ring  as  a  nucleus  are  the  five  alkaloids  of  Conium  macu- 
latum,  coniine,C8H17N,  conhydrine,  C8H17NO,  coniceine,  C8Hir,X, 
tt-methyl-coniine,  C9H19N,  and  pseudoconhydrine,  C8H17NO;  and 
two  of  the  four  betel-nut  alkaloids:  arecaine,  C7H11N02,  and  guva- 
cine,  C6H9N02. 

Coniine — C8H17N — is  one  of  the  most  simply  constituted  of  the 
natural  vegetable  alkaloids,  and  was  the  first  to  be  produced  synthet- 
ically. It  is  a  colorless,  oily  liquid;  has  an  acrid  taste  and  a  dis- 
agreeable, penetrating  odor ;  sp.  gr.  0.844 ;  can  be  distilled  when  pro- 
tected from  air ;  b.  p.  166  °.  Exposed  to  air  it  resinifies.  The  natural 
alkaloid  is  d-conime,  [#]  D=15.7°.  It  is  very  sparingly  soluble  in 
water,  but  is  more  soluble  in  cold  than  in  hot  water;  soluble  in  all 
proportions  in  alcohol,  easily  soluble  in  ether,  and  in  fixed  and 
volatile  oils. 

Its  vapor  at  ordinary  temperatures  forms  a  white  cloud  when  in 
contact  with  a  glass  rod  moistened  with  HC1,  as  does  NH3.  It  forms 
salts  which  crystallize  with  difficulty.  Chlorine  and  bromine  combine 
with  it  to  form  crystallizable  compounds ;  iodine  in  alcoholic  solution 
forms  a  brown  precipitate  in  alcoholic  solutions  of  coniine,  which  is 
soluble  without  color  in  an  excess.  Ethyl  and  methyl  iodides  combine 
with  it  to  form  crystallizable  compounds;  iodine  in  alcoholic  solution 
forms  a  brown  precipitate  in  alcoholic  solutions  of  conime,  which  is 
soluble  without  color  in  an  excess.  Ethyl  and  methyl  iodides  combine 
with  it  to  form  ethyl-  and  methyl-coniine  hydriodides. 

It  has  been  obtained  synthetically  from  a-picoline  by  reactions 
which  show  it  to  be  <*-propyl  piperidine.  The  relations  of  pyridine, 
piperidine,  and  conime  are  shown  by  the  following  formulae : 

H  H,  H2 

C  C  C 

/\\  /\  /\ 

HC        CH  H2C        CH2  H2C        CH2 

HC        CH  H2C        CH2  H2C        CHC8HT 

\//  \/  \/ 

N  N  N 

H  H 

Pyridine.  Piperidine.  Coniine. 

ANALYTICAL  CHARACTERS — .(1)  With  dry  HC1  gas  it  turns  red- 
dish-purple, and  then  dark-blue.  (2)  Aqueous  HC1  of  sp.  gr.  1.12 
evaporated  from  coniine  leaves  a  green-blue,  crystalline  mass.  (3) 
With  iodic  acid:  a  white  ppt.  from  alcoholic  solutions.  (4)  With 
H2SO4  and  evaporation  of  the  acid:  a  red  color,  changing  to  green, 
and  an  odor  of  butyric  acid.  (5)  When  mixed  with  commercial 
nitrobenzene  a  fine  blue  color  is  produced,  changing  to  red  and 
yellow. 


ALKALOIDS  423 

Paraconiine — C8H15N — is  a  synthetical  product  closely  resembling 
coni'ine,  Obtained  by  first  allowing  butyric  aldehyde  and  an  alcoholic 
solution  of  ammonia  to  remain  some  months  in  contact  at  30°,  when 
dibutyraldine  is  formed:  2(C4H80)+NH8=C8H17NO+H20.  The 
dibutyraldine  thus  obtained  is  then  heated  under  pressure  to  150°- 
180  °,  when  it  loses  water,  and  forms  paraconiine :  C8H17NO= 
C8H15N-|-H20.  A  synthesis  which,  in  connection  with  the  decom- 
positions of  paraconiine,  shows  its  rational  formula  to  be  *  4H7  yN. 

Pipeline — C17H19N03 — isomeric  with  morphine,  and  occurring  in 
black  and  white  pepper,  crystallizes  in  large  prisms;  f.  p.  128°; 
almost  insoluble  in  water,  readily  soluble  in  alcohol  and  in  ether.  It 
is  a  weak  base,  without  alkaline  reaction,  and  only  forming  very  un- 
stable salts  with  concentrated  acids.  It  is  one  of  the  alkaloids  whose 
complete  synthesis  has  been  accomplished,  and  is  quite  directly  de- 
rived from  piperidine,  of  which  it  is  an  n-acidyl  derivative.  When 
piperine  is  heated  with  alcoholic  soda,  it  is  hydrolyzed  into  piperic 
acid,  C12H1004,  and  piperidine.  It  is  therefore  piperidine  piperate, 
or  piperidine-3,  4-methylene-dioxy-cinnamyl-acrylate : 

H  H2  H2 

C  C  C  C Ox 

/\\  /\  /\  /\\  >CH2 

HC        CH  H2C         CH2  H2C        CH2  HC        C— 0  / 

HC        CH  H2C        CH2  H2C         CH2  HC        CH 

\//  \/  \/  \// 

N  N  N  C 

H  CO  .  CH  :  CH  .  CH  :  CH 

Pyridine.  Piperidine.  Tiperine. 

Pyrrolidine-pyridine  Alkaloids  are  represented  by 
Nicotine — C10H14N2 — which  exists  in  tobacco  in  the  proportion  of 
2-8  per  cent.  It  is  a  colorless,  oily  liquid,  which  turns  brown  on 
exposure  to  air,  has  a  burning,  caustic  taste,  and  a  disagreeable, 
penetrating  odor.  It  distils  at  250°;  burns  with  a  luminous  flame; 
sp.  gr.  1.027  at  15°;  is  very  soluble  in  water,  alcohol,  the  fatty  oils, 
and  ether.  The  last-named  fluid  removes  it  from  its  aqueous  solu- 
tion when  the  two  are  shaken  together.  It  absorbs  water  rapidly 
from  moist  air.  Its  salts  are  deliquescent,  and  crystallize  with  diffi- 
culty. The  natural  alkaloid  is  1-nicotine.  The  i-nicotine  has  been 
obtained  by  total  synthesis,  through  /5-amidopyridine.  From  this 
1-nicotine  is  produced  by  the  action  of  tartaric  acid. 

The  oxidation  of  nicotine  produces  nicotinic,  or  (3  monocarbo- 
pyridic,  acid.  When  distilled  with  zinc  chloride  and  lime  it  yields 
pyrrole,  ammonia,  methylamine,  hydrogen,  and  pyridine  bases.  When 
heated  to  250°  it  yields  a  collidine  along  with  other  products.  By 
limited  oxidation  it  produces  a  substance,  C10H10N2,  formerly  con- 


424  TEXT-BOOK  OF   CHEMISTRY 

sidered  as  isodipyridine,  but  shown  to  be    /?-pyridine-n-methyl-a- 
pyrrole, 

(~I-TT /^TT  r^TT        PTI 

.  U-tl — V^Xl .  //  V^Xl 

HC<  >C— C('  || 

NXN  -CH//  XN(CH3)CH 

of  which  nicotine  is  the  tetrahydro,  or  pyrrolidine  derivative — 

f!H=CIL  ,  CH2        — CH2 

\C— CH/ 


— CH2 


ANALYTICAL  CHARACTERS. —  (1)  Its  ethereal  solution,  added  to 
an  ethereal  solution  of  iodine,  separates  a  reddish-brown,  resinoid  oil, 
which  gradually  becomes  crystalline.  (2)  With  HC1,  a  violet  color. 
(3)  With  HN03,  an  orange  color. 

TOXICOLOGY. — Nicotine  is  a  very  active  poison.  The  free  alkaloid  is  prob- 
ably capable  of  causing  death  in  doses  of  two  to  three  drops.  It  was  the 
first  alkaloid  to  be  separated  from  the  cadaver  in  a  case  of  homicide.  Most 
cases  of  poisoning  from  nicotine  are  due  to  tobacco,  frequently  resulting  from 
its  use  in  enemata.  When  administered  to  dogs  in  doses  of  two  to  four  drops,  its 
effects  begin  within  half  a  minute  to  two  minutes,  and  death  ensues  within 
one  to  five  minutes.  In  man  tobacco  or  its  decoction  causes  nausea,  vertigo, 
dilatation  of  the  pupils,  vomiting,  syncope,  diminution  of  the  rapidity  and 
force  of  the  heart.  With  large  doses  there  are  no  subjective  symptoms,  the 
victim  falls  unconscious  instantly,  and  dies  within  five  minutes,  without  con- 
vulsions, and  with  very  few  or  only  one  deep  sighing  respiratory  act.  The 
1-nicotine  has  double  the  toxic  power  of  d-nicotine,  and  the  two  forms  differ  in 
the  nature  of  the  action  produced. 

Pyrrolidine-piperidine  Alkaloids — Tropan  Alkaloids. — The  alka- 
loids of  this  group,  most  of  which  are  ester-alkaloids,  including  the 
atropic  alkaloids,  atropine,  hyoscyamine,  and  hyoscine,  and  the  coca 
alkaloids,  ecgonine,  cocaine,  cinnamyl-cocame,  a-  and  ^-truxillines, 
benzoylecgonine  and  tropacocai'ne,  are  derivatives  of  tropan  (1),  the 
ri-methyl  derivative  of  nortropan  (2),  both  of  which  are  known,  as 
well  as  many  of  their  compounds  other  than  alkaloids : 

H, 
C 
\  H2C— CH CH, 


H2C—  HC       CH2 


HN 


or 
CH2 


| 


—  C 


CH, 

I 


\  /  H,C— CH CH, 

H,0 C  H2C C 

H 

(2) 

Nortropan  may  be  considered  as  formed  by  condensation  of  a 
pyrrolidine  ring  and  a  piperidine  ring,  having  the  group  =CII.NH.- 
('11=  in  common.  The  following  tropan  derivatives  are  of  interest 
in  connection  with  the  syntheses  of  atropic  and  coca  alkaloids. 


ALKALOIDS  425 

Tropidine — (formula  below) — is  a  dehydrotropan,  first  obtained 
as  a  product  of  decomposition  of  atropine,  and  later  of  cocaine,  thus 
indicating  the  relationship  of  the  two  alkaloids.  It  has  been  obtained 
by  total  synthesis,  starting  from  synthetic  glycerol  (p.  223),  through 
allyl  bromide,  trimethylene  bromide,  trimethylene  cyanide,  glutaric 
acid  (p.  259),  to  suberone  (formula  below).  From  suberone  to  tro- 
pidine  many  steps  are  required,  the  principal  intermediate  products 
being  cycloheptene  (2),  cycloheptatriene,  and  ^-methyltropidine : 


H2C.CH2.CO  H2C.CH2.CH  H2C.CH CH 

iGH2  CH                             N.CH3  CH 

.CH2.CH2  H2C.CH2.CH2  H2C.CH CH3 

Suberone.  Cycloheptene.                                  Tropidine. 


Tropine — (formula  p.  426) — 4-Tropan  Alcohol  —  is  formed 
through  its  space  isomere,  ^-tropine,  by  conversion  of  tropidine  into 
a  dibromo  addition  product,  and  splitting  off  of  Bf2  and  addition  of 
H20  by  heating  with  H2S04  at  200°.  Tropine  is  the  alcoholic  com- 
ponent of  atropine,  hyoscyamine  and  the  tropeines,  and  of  which 
ecgonine  (p.  427)  is  the  carboxylic  acid. 

Atropine — i-Tropine  tropate — C17H23N03. — Belladonna,  stramo- 
nium, hyosyamus  and  duboisia  contain  five  alkaloids:  atropine, 
hyoscyamine,  hyoscine,  scopolamine  and  belladonnine,  of  which  the 
first  two  are  optical  isomeres  of  each  other. 

Atropine  forms  colorless,  silky  needles,  sparingly  soluble  in  cold 
water,  more  readily  in  hot  water,  very  soluble  in  chloroform.  It  is 
odorless,  has  a  disagreeable,  persistent,  bitter  taste.  Both  tropine  and 
tropic  acid  (see  below)  contain  an  asymmetric  carbon  atom.  The 
tropine  in  atropine  is  i-tropine,  and  the  acid  is  d-tropic  acid.  Both 
natural  and  synthetic  atropines  are  optically  inactive.  Atropine  is 
distinctly  alkaline,  and  neutralizes  acids  with  formation  of  salts.  The 
sulphate  is  a  white,  crystalline  powder,  readily  soluble  in  water. 

Atropine  is  the  type  of  the  "ester  alkaloids"  saponifiable  into  an 
acid  and  an  alcoholic  component.  When  it  is  acted  upon  by  Ba(OH)2 
at  60°,  or  by  NaOH  or  HC1  at  120°-130°,  it  is  saponified,  after  the 
manner  of  an  ester,  into  tropic,  or  a-phenylhydracrylic  acid, 

C6H5.CH  \CHOH  '  anc^  a  secondary  cyclic  alcohol,  tropine  (formula 
below).  But  if  the  action  be  prolonged  the  tropic  acid  is  further 
decomposed  into  or-phenylacrylic,  or  atropic,  and  isatropic  acids. 
And  if,  during  the  action  of  HC1,  the  temperature  rises  to  180°,  the 
tropine  loses  water,  and  is  converted  into  tropidine. 

The  relation  of  atropine  to  its  progenitors  is  shown  in  the  fol- 
lowing formulae: 


426 


TEXT-BOOK   OF    CHEMISTRY 


H2C.CH CH2 

iN.CH3  CH2 
.CH CH2 

Tropan. 


H2C.CH  CH 

H2C.CH  CH2 

N.CHs  CH 

N.CH3  CHOH 

H2C.CH  CH2 

H2C.CH  CH3 

Tropidine. 

Tropine. 

H 

H2C.CH— 

—  CH2                                C 

N.CHs 

I                                  //\ 
CH.OOC.CH  C        CH 

H2C.CH  

-CH2         CH2  OH  HC        CH 

\\/ 

C 

H 

Tropine  tropate  —  Atropine. 

HOOC.CH C        CH 

CH2OH    HC        CH 

V 

H 

Tropic  Acid. 

ANALYTICAL  CHARACTERS. —  (1)  If  a  fragment  of  potassium  di- 
chromate  is  dissolved  in  a  few  drops  of  H2S04,  the  mixture  warmed, 
a  fragment  of  atropine  and  a  drop  or  two  of  H20  added,  and  the  mix- 
ture stirred,  an  odor  of  orange-blossoms  is  developed.  (2)  A  solu- 
tion of  atropine  dropped  upon  the  eye  of  a  cat  produces  dilatation 
of  the  pupil.  (3)  The  dry  alkaloid  (or  salt)  is  moistened  with  fum- 
ing HN03  and  the  mixture  dried  on  the  water-bath.  When  cold,  it  is 
moistened  with  an  alcoholic  solution  of  KOH ;  a  violet  color,  which 
changes  to  red  (Vitali).  (4)  If  a  saturated  solution  of  Br  in  HBr 
is  added  to  a  solution  of  atropine,  a  yellow  precipitate  is  formed, 
which  rapidly  becomes  crystalline,  and  which  is  insoluble  in  acetic 
acid,  sparingly  soluble  in  H2S04  and  HC1. 

TOXICOLOGY. — The  clinical  history  of  atropic  poisoning  is  divisible  into  two 
stages,  the  first  one  of  delirium,  in  which  the  prominent  symptoms  are  dryness 
of  the  throat,  thirst,  difficulty  of  deglutition  and  spasms  upon  swallowing 
liquids,  face  at  first  pale,  afterwards  highly  reddened,  pulse  extremely  rapid, 
eyes  prominent,  brilliant,  with  widely-dilated  pupils,  complete  paralysis  of 
accommodation,  disturbances  of  vision,  attacks  of  giddiness  and  vertigo,  with 
severe  headache,  followed  by  delirium,  occasionally  silent  or  muttering,  but 
usually  violent,  noisy  and  destructive,  accompanied  by  the  most  fantastic  de- 
lusions and  hallucinations.  Usually  the  urine  is  retained,  and  the  body  tem- 
perature is  above  the  normal.  The  delirium  gradually  subsides,  and  the  second 
stage,  that  of  coma,  is  established,  with  slow,  stertorous  respiration,  and  grad- 
ually failing  pulse,  until  death  occurs  from  respiratory  or  cardiac  paralysis, 
or  sometimes  in  an  attack  of  syncope  during  apparent  amelioration.  In  some 
cases,  the  patient  rapidly  becomes  comatose  at  the  outset,  and  the  symptoms 
of  the  first  stage  are  manifested  as  the  coma  diminishes.  The  treatment  should 
consist  of  lavage  of  the  stomach,  and  morphine  may  be  given  cautiously  during 
the  period  of  violent  excitement.  In  the  second  stage,  the  treatment  is  the 
same  as  in  morphine  poisoning.  Pilocarpine  may  be  given,  in  not  too  large  doses, 
to  stimulate  the  secretion  of  saliva.  Atropic  poisoning  leaves  no  characteristic 
post-mortem  lesions. 

Hyoscyamine — C17H23N03 — isomeric  with  atropine,  predominates 
in  Hyoscyamus  niger,  and  in  m&ndragora.  It  differs  from  atropine 


ALKALOIDS  427 

principally  in  being  laevogyrous,  [>]D  = — 20.3°,  and  on  saponifica- 
tion  it  yields  1-tropic  acid  and  i-tropine.  It  is  converted  into 
atropine  very  easily,  by  heat,  or  by  addition  of  alkali  to  its  alcoholic 
solution. 

Apoatropine — Atropamine  —  Tropine  atropate  —  C17H21N02 — is 
formed  by  the  action  of  dehydrating  agents,  H2S04,  P205,  etc.,  on 
atropine  or  hyoscyamine,  by  splitting  off  of  H20  from  the  acid  com- 
ponent, thus  converting  the  residue  of  the  saturated  tropic  acid  into 
that  of  the  unsaturated  atropic  acid.  By  heat  it  is  converted  into  its 
isomere,  belladonnine,  an  alkaloid  which  accompanies  atropine  in 
belladonna.  Hyoscine  and  scopolamine,  C17H2104,  are  two  iso- 
meric,  mydriatic  alkaloids,  accompanying  atropine  in  belladonna. 
The  latter  on  decomposition  yields  tropic  acid  and  scopoline,  C8H13- 
N02,  which  is  closely  related  to  tropine,  C8H15NO. 

Tropei'nes — are  ester-like  derivatives  of  tropine  with  acids,  similar 
to  atropine.  Many  such  have  been  formed  with  organic  acids,  ben- 
zoic,  salicylic,  etc.  That  formed  with  mandelic  acid  is  known  as 
homatropine,  C8H14N.OOC.CH(OH).C6H5,  is  used  as  a  mydriatic 
having  a  less  prolonged  action  than  atropine.  Only  those  tropeines 
whose  acid  radicals  contain  an  alcoholic  hydroxyl  have  a  mydriatic 
action. 

Ecgonine — C9H15N03 — an  alkaloid  existing  in  Eryfhroxylon  coca, 
and  the  parent  substance  of  cocaine  and  other  coca  alkaloids,  is  4- 
oxytropan-5-monocarboxylic  acid  (p.  428).  By  the  action  of  dehy- 
drating agents  upon  ecgonine  the  alcoholic  OH  and  an  H  atom  are 
split  off,  and  anhydroecgonine,  C9H13N02,  is  formed,  which,  by  split- 
ting off  of  C02  from  the  carboxyl,  forms  tropidine.  Ecgonine,  being 
both  basic  and  acid,  forms  esters  and  salts,  and  numerous  products  of 
derivation  other  than  cocaine.  When  acted  upon  by  a  mixture  of 
methyl  iodide  and  benzoic  anhydride,  ecgonine  is  converted  into 
cocaine.  Or  by  substitution  of  other  alkyl  iodides  for  that  of  methyl, 
other  alkaloids,  homologous  with  cocaine,  are  obtained  (see  formulae 
below) . 

Cocaine — C17H21N04 — the  most  important  of  the  coca  alkaloids,  is 
closely  related  chemically  to  atropine.  It  crystallizes  in  large  four- 
or  six-sided  prisms;  f.  p.  98°;  sparingly  soluble  in  water,  readily 
soluble  in  alcohol,  ether  and  chloroform ;  somewhat  bitter  at  first,  but 
causing  paralysis  of  the  sense  of  taste  afterwards;  strongly  alkaline. 
Its  hydrochloride,  used  as  a  local  anesthetic,  crystallizes  in  prismatic 
needles,  readily  soluble  in  water. 

When  boiled  with  water,  cocaine  is  hydrolyzed  into  benzoylecgo- 
nine,  C16H19N04,  and  methylic  alcohol.  If  the  hydrolysis  is  effected 
by  Ba(OH)2,  or  by  concentrated  mineral  acids,  it  is  more  complete, 
and  ecgonine,  benzoic  acid  and  methylic  alcohol  are  formed.  Cocaine 
is,  therefore,  the  methyl  ester  of  benzoylecgonine,-  and  ecgonine  is 
tropine-5-monocarboxylic  acid: 


428 


TEXT-BOOK   OF    CHEMISTRY 


Tropidlne. 


H2C.CH- 


Anhydroecgouine. 
Tropidine-5-carboxylic  acid. 


Tropine. 


N.CH8      C 


^H.COOH 
HOH 


H2C.CH- 

Ecgonine. 
Tropine-5-carboxylic    acid. 


H.COO.CH, 
CHO.CO.CaH6 

k 


Cocaine. 
Methyl    benzoylecgonate. 


ANALYTICAL  CHARACTERS. — (1)  Picric  acid  forms  a  yellow  ppt.  in 
concentrated  solutions.  (2)  A  solution  of  iodine  in  KI  solution  gives 
a  fine  red  precipitate  in  a  solution  containing  1  to  10,000  of  cocaine. 
(3)  When  cocaine  hydrochloride  is  heated  with  concentrated  H2S04 
until  white  fumes  are  given  off  abundantly,  and  potassium  iodate  is 
added  to  the  still  hot  liquid,  abundant  violet  vapors  are  given  off,  and 
the  liquid  becomes  deep  red-violet,  changing  to  brilliant  green,  then 
to  pink,  and  finally  to  pure  blue-violet.  (4)  Potassium  permanganate 
produces  a  violet,  crystalline  ppt.  (5)  A  5  per  cent,  solution  of 
chromic  acid  produces  an  orange-colored  ppt.,  which  immediately 
redissolves,  but,  after  addition  of  HC1,  remains  permanent.  (6)  If 
cocaine  hydrochloride  is  mixed  dry  with  HgCl,  the  white  mixture  in 
moist  air  turns  gray  or  black.  Pilocarpine  gives  the  same  reaction. 

Pilocarpine — CnH16N202 — occurs  in  jaborandi,  along  with  two 
other  alkaloids,  jaborine,  C22H32N404(  ?),  and  pilocarpidine,  C10H14- 
N202,  and  an  essential  oil,  consisting  principally  of  pilocarpene, 
C10H16.  It  is  colorless,  crystalline,  readily  soluble  in  water,  alcohol, 
ether  and  chloroform.  It  is  converted  by  heat  into  jaborine;  and  by 
HN03  or  HC1  into  a  mixture  of  jaborine  and  jaborandine,  C10H12- 
N203.  Like  piperine,  atropine,  cocaine,  etc.,  it  is  ethereal  in  char- 
acter and  is  decomposed  into  C02,  methylamine,  butyric  acid,  and 
pyridine  bases  by  KOH  or  NaOH.  When  oxidized  by  potassium 
permanganate  it  yields  pyridine-tartronic  acid,  C6H4N.C.:(OH)- 
(COOH)2,  and  this,  on  further  oxidation,  nicotinic  acid,  C5H4N.- 
COOH.  When  its  hydrochloride  is  heated  to  200°,  in  presence  of 
H2O,  it  takes  up  water  and  is  decomposed  into  pilocarpidine  and 
methylic  alcohol.  Conversely,  pilocarpine  is  produced  by  the  action 
of  methyl  iodide  upon  pilocarpidine.  Although  the  constitution  of 
pilocarpine  is  not  established,  the  above  and  other  reactions  indicate 
that  it  contains  the  pyridine  ring,  to  which  the  cyclic  group, 
C6H12N02,  is  attached  in  the  ft  position;  and  that  it  is  methyl- 
pilocarpidine. 

Quinoline  Alkaloids — Cinchona  Alkaloids. — Although  by  no 
means  so  complex  a  substance  as  opium,  cinchona  bark  contains  a 


ALKALOIDS  429 

great  number  of  substances :  quinine,  cinchonine,  quinidine,  cinchoni- 
dine,  aricine;  quinic,  quinotannic  and  quinovic  acids;  cinchona-red, 
etc.  Of  these  the  most  important  are  quinine  and  cinchonine. 

Quinine— Quinina  (U.  S.  P.)— C20H24N202+n  Aq— 324+wl8  ex- 
ists in  the  bark  of  a  variety  of  trees  of  the  genera  cinchona  and 
China,  which  vary  considerably  in  their  richness  in  this  alkaloid. 
The  best  samples  of  calisaya  bark  contain  from  30  to  32  parts  per 
1,000  of  the  sulphate;  the  intermediate  grades  4  to  20  parts  per 
1,000;  inferior  grades  of  bark  contain  from  mere  traces  to  6  parts 
per  1,000. 

It  is  known  in  three  different  states  of  hydration,  with  1,  2,  and  3 
Aq,  and  anhydrous.  The  anhydrous  form  is  an  amorphous,  resinous 
substance,  obtained  by  evaporation  of  solutions  in  anhydrous  alcohol 
or  ether.  The  first  hydrate  is  obtained  in  crystals  by  exposing  to 
air  recently  precipitated  and  well-washed  quinine.  The  second  by 
precipitating  by  ammonia  a  solution  of  quinine  sulphate,  in  which  H 
has  been  previously  liberated  by  the  action  of  Zn  upon  H2S04 ;  it  is  a 
greenish,  resinous  body,  which  loses  H20  at  150°.  The  third,  that  to 
which  the  following  remarks  apply,  is  formed  by  precipitating  solu- 
tions of  quinine  salts  with  ammonia. 

It  crystallizes  in  hexagonal  prisms;  very  bitter;  fuses  at  57°; 
loses  1  Aq  at  100°,  and  the  remainder  at  125°;  becomes  colored, 
swells  up,  and,  finally,  burns  with  a  smoky  flame.  It  does  not 
sublime.  It  dissolves  in  2,200  pts.  of  cold  water,  in  763  of  hot  water, 
very  soluble  in  alcohol  and  chloroform;  soluble  in  amyl  alcohol, 
benzene,  fatty  and  essential  oils,  and  ether.  Its  alcoholic  solution  is 
powerfully  laBvogyrous,  [a.]Di=  —  270.7°  at  18°,  which  is  diminished 
by  increase  of  temperature,  but  increased  by  the  presence  of  acids. 

ANALYTICAL  CHARACTERS. —  (1)  Dilute  H2S04  dissolves  quinine 
in  colorless  but  fluorescent  solution  (see  below).  (2)  Solutions  of 
quinine  salts  turn  green  when  treated  with  chlorine-water  and  then 
with  ammonium  hydroxide.  (3)  Chlorine  passed  through  water  hold- 
ing quinine  in  suspension  forms  a  red  solution.  (4)  Solution  of 
quinine  treated  with  chlorine-water  and  then  with  fragments  of  po- 
tassium ferrocyanide  becomes  pink,  passing  to  red. 

SULPHATE— Quininae  sulphas  (U.  S.  PO^(C20H24paNt)r18H2SO4-H 
7  Aq — 746-J-126 — crystallizes  in  prismatic  needles;  very  light;  in- 
tensely bitter :  phosphorescent  at  100  ° ;  fuses  readily ;  loses  its  Aq 
at  120°,  turns  red,  and  finally  carbonizes;  effloresces  in  air,  losing 
6  Aq ;  soluble  in  740  pts.  of  water  at  13  °,  in  30  pts.  of  boiling  water, 
and  60  pts.  of  alcohol.  Its  solution  with  alcoholic  solution  of  iodine 
deposits  brilliant  green  crystals  of  iodoquinine  sulphate. 

HYDRO-SULPHATE — Quininae  bisulphas  (U.  S.  P.) — C20H2402N2.- 
H2S04+7  Aq  —422+126— is  formed  when  the  sulphate  is  dissolved 
in  excess  of  dilute  H2S04.  It  crystallizes  in  long,  silky  needles,  or  in 
short,  rectangular  prisms;  soluble  in  10  pts.  of  water  at  15°.  Its 


430  TEXT-BOOK   OF   CHEMISTRY 

solutions  exhibit  a  marked  fluorescence,  being  colorless,  but  showing  a 
fine  pale-blue  color  when  illuminated  by  a  bright  light  against  a 
dark  background. 

By  the  action  of  alkaline  hydroxides  upon  quinine,  formic  acid, 
quinoline,  and  pyridine  bases  are  produced. 

Concentrated  HC1  at  140°-150°  decomposes  quinine  with  separa- 
tion of  methyl  chloride  and  formation  of  apoquinine,  C19H22N202,  an 
amorphous  base. 

Oxidizing  agents  produce  from  quinine  oxalic  acid  and  pyridine 
carboxylic  acids,  notably  pyridine-2  3-dicarboxylic,  or  cinchomer- 
onic  acid,  C5H3N(COOH)2,  which  are  also  formed  by  oxidation  of  cin- 
chonine. 

Although  cinchonine  differs  from  quinine  in  composition  by 
CH20,  and  although  the  decompositions  of  the  two  bases  show  them 
both  to  be  related  to  the  quinoline  and  pyridine  bases,  attempts  to 
convert  cinchonine  into  quinine  have  resulted  only  in  the  formation 
of  other  products,  among  which  is  an  isomere  of  quinine,  oxycin- 
chonine. 

Methylquinine,  C20H24N202CH3,  is  a  base  which  has  a  curare-like 
action. 

Cinchonine — Cinchonina  (U.  S.  P.) — C19H22N20 — 294 — occurs  in 
Peruvian  bark  to  the  amount  of  from  2  to  30  pts.  per  1,000.  It  crys- 
tallizes without  Aq  in  colorless  prisms;  fuses  at  150°;  soluble  in 
3,810  pts.  of  water  at  10°,  in  2,500  pts.  of  boiling  water;  in  140  parts 
of  alcohol,  and  in  40  pts.  of  chloroform.  The  salts  of  cinchonine 
resemble  those  of  quinine  in  composition;  are  quite  soluble  in  water 
and  in  alcohol;  are  not  fluorescent;  are  permanent  in  air;  and  are 
phosphorescent  at  100°. 

Quinidine  and  Quinicine — are  bases  isomeric  with  quinine;  the 
former  occurring  in  cinchona  bark,  and  distinguishable  from  quinine 
by  its  strong  dextrorotary  power ;  the  second  a  product  of  the  action 
of  heat  on  quinine,  not  existing  in  cinchona. 

Cinchonidine — a  base,  isomeric  with  cinchonine,  occurring  in  cer- 
tain varieties  of  bark,  laevogyrous.  At  130°,  H2S04  converts  it  into 
another  isomere,  cinchonicine. 

Constitution  of  Cinchona  Alkaloids. — The  constitution  of  no 
cinchona  alkaloid  has  yet  been  completely  determined.  Enough  has, 
however,  been  ascertained  to  show  that  cinchonine  and  quinine  con- 
tain a  quinoline  nucleus,  united  to  another  cyclic  nucleus,  containing 
the  second  N  atom,  and  which  is  probably  a  modified  piperidinc.  The 
difference  between  the  empirical  formula?  of  cinchonine,  C19H22N20, 
and  of  quinine,  C20H24N202,  is  CH20  in  favor  of  the  latter,  which 
would  represent  the  substitution  of  methoxyl,  CH3O,  for  H.  When 
cinchonine  and  quinine  are  oxidized  by  chromic  acid  they  yield  two 
quinoline-carboxylic  acids  also  differing  from  each  other  by  CH,O. 
Cinchonine  yields  cinchoninic  acid,  which  is  known  to  be  p-qumoline 


ALKALOIDS 


431 


carboxylic  acid;  while  quinine  yields  quinic  acid,  which  has  been 
shown  to  be  the  methyl-phenol  ether  of  p-oxyquinoline-  ^-carboxylic 
acid  (see  formula?,  below).  Therefore  the  group  CH20,  by  which 
cinchonine  and  quinoline  differ,  exists  in  the  quinoline  ring,  and  the 
"second  half,"  or  the  portion  of  the  molecule  other  than  the  quino- 
line ring,  is  the  same  in  the  two  alkaloids.  This  is  further  proved  by 
the  fact  that  on  decomposition  by  PC15  and  subsequent  treatment 
with  alcoholic  KOH,  cinchonine  yields  lepidine,  C10H9N,  the  next 
superior  homologue  of  quinoline,  C9H7N,  while  quinine  yields  p- 
methoxy-lepidine,  C10H8(OCH3)N,  and  the  other  product  of  the  de- 
composition is  one  and  the  same  substance  from  either  alkaloid,  a 
substance  which  has  been  called  meroquinene,  C9H15N02,  which  on 
treatment  with  HgCl2  and  HC1  is  converted  into  /?-ethyl-;/-methyl- 
pyridine,  and  whose  probable  constitution  is  expressed  by  the  for- 
mula given  below.  So  far  as  determined,  therefore,  the  formula 
of  cinchonine  and  of  quinine  are  those  here  given,  the  arrangement 
•  of  the  group  C10H15(OH)N  remaining  to  be  determined: 


H        COOH 


/\\ 
HC        C        CH 

ml      H 

\\/ 

C        N 
H 

Cinchoninic  acid, 
(y-quinoline  car- 
boxylic acid). 


H        COOH 


CH3 

(! 


/\\ 
CH3O.C         C         CH 

y 

\\/ 

C        N 


Quinic  acid,    (3-Meth- 
oxyquinoline       y  -car- 
boxylic  acid). 


C10H15(OH)N 


H     CHa.COOH 
\/ 
C 

/\     /H 
H2C        C< 

I  \CH:CHa 


j 


H2C        CH2 
\/ 

N 


Meroquinene  (?) 


H        C10H16(OH)N 


HC        C— CH2.CH, 

HC        CH 

\\/ 

N 


6  -Ethyl-y-methyl-pyridine. 


HC 


/\\ 
C        CH 


\\/ 

C        N 


Cinchonine. 


CH30— C        C        CH 

I         II          I 
HC        C        CH 

V  Y 
A 

Quinine. 


Alkaloids  of  the  Loganiaceae — Strychnos  Alkaloids. — This  group 
includes  strychnine  and  brucine  and  their  alkyl  derivatives,  and  the 
curare  alkaloids. 

Strychnine — C21H22N202 — exists  in  the  seeds  and  bark  of  different 
varieties  of  Strychnos,  notably  Strychnos  nux-vomica. 

It  crystallizes  on  slow  evaporation  of  its  solutions  in  orthorhombic 
prisms ;  very  sparingly  soluble  in  water  and  in  strong  alcohol ;  soluble 


432  TEXT-BOOK   OF    CHEMISTRY 

in  5  parts  of  chloroform.    Its  aqueous  solution  is  intensely  bitter,  the 
taste  being  perceptible  in  a  solution  containing  1  part  in  200,000. 

It  is  a  powerful  base;  neutralizes  and  dissolves  in  concentrated 
H2S04  without  coloration,  and  precipitates  many  metallic  oxides  from 
solutions  of  their  salts.  Its  salts  are  mostly  crystallizable,  soluble  in 
water  and  in  alcohol,  and  intensely  bitter.  The  acetate  is  the  most 
soluble.  The  neutral  sulphate  crystallizes,  with  7  Aq,  in  rectangular 
prisms.  Methyl  and  ethyl  iodides  react  with  strychnine  to  produce 
methyl  or  ethylstrychnium  iodides,  white,  crystalline  substances, 
producing  an  action  on  the  economy  similar  to  that  of  curare.  Heated 
with  fuming  HN03,  strychnine  yields  picric  acid.  Heated  with 
baryta  water  to  130°,  it  yields  isostrychnic  acid,  C20H23N2O.COOH; 
and  when  treated  with  sodium  alcoholate,  strychnic  acid,  by  addition 
of  H20.  By  boiling  with  concentrated  hydriodic  acid  and  red  phos- 
phorus it  is  converted  into  desoxystrychnine,  C21H20N20,  which  is 
further  reduced  by  electrolysis  to  dihydrostrychnoline,  C21H28N2. 
Strychnine  itself,  by  electrolysis,  forms  two  bases,  tetrahydro- 
strychnine,  C21H2CN202,  and  strychnidine,  C21H24N20.  But  little  is 
known  of  the  constitution  of  strychnine,  which  is,  however,  probably 
a  derivative  of  tetrahydroquinoline. 

ANALYTICAL  CHARACTERS.— (1)  Dissolves  in  concentrated  H2S04, 
without  color.  The  solution  deposits  strychnine  when  diluted  with 
water,  or  when  neutralized  with  magnesia  or  an  alkali.  (2)  If  a 
fragment  of  potassium  dichromate  (or  other  substance  capable  of 
yielding  nascent  oxygen)  is  drawn  through  a  solution  of  strychnine 
in  H2S04,  it  is  followed  by  a  streak  of  color;  at  first  blue  (very  transi- 
tory and  frequently  not  observed),  then  a  brilliant  violet,  which 
slowly  passes  to  rose-pink,  and  finally  to  yellow.  Reacts  with  %oooo 
grain  of  strychnine.  (3)  A  dilute  solution  of  potassium  dichromate 
forms  a  yellow,  crystalline  ppt.  in  strychnine  solutions,  which,  when 
washed  and  treated  with  concentrated  H2S04,  gives  the  play  of  colors 
indicated  in  2.  (4)  If  a  solution  of  strychnine  is  evaporated  on  a  bit 
of  platinum  foil,  the  residue  moistened  with  concentrated  H2S04,  the 
foil  connected  with  the  -f-  pole  of  a  single  Grove  cell,  and  a  platinum 
wire  from  the  —  pole  brought  in  contact  with  the  surface  of  the  acid, 
a  violet  color  appears  upon  the  surface  of  the  foil.  (5)  Strychnine 
and  its  salts  are  intensely  bitter.  (6)  A  solution  of  strychnine  in- 
troduced under  the  skin  of  the  back  of  a  frog  causes  difficulty  of 
respiration  and  tetanic  spasms,  which  are  aggravated  by  the  slightest 
irritation,  and  twitching  of  the  muscles  during  the  intervals  between 
the  convulsions.  With  a  small  frog,  Vioooo  grain  of  strychnine  acetate 
will  produce  tetanic  spasms  in  ten  minutes.  White  mice,  14  to  16 
days  old,  are  even  more  susceptible  to  the  action  of  strychnine  than 
frogs.  (7)  Solid  strychnine,  moistened  with  a  solution  of  iodic  acid 
in  H2S04,  produces  a  yellow  color,  changing  to  brick-red,  and  then  to 
violet-red.  (8)  Moderately  concentrated  HN03  colors  strychnine 


ALKALOIDS  433 

yellow  in  the  cold.  (9)  A  warm  solution  of  strychnine  in  dilute  HN03 
produces  a  scarlet-red  color  on  addition  of  a  little  KC103.  A  drop  or 
two  of  ammonia  changes  this  to  brown.  On  evaporation  to  dryness, 
green  residue  remains,  which  forms  a  green  solution  in  water,  changes 
to  orange-brown  with  KOH,  and  returns  to  green  with  HN03. 

TOXICOLOGY.— Strychnine  produces  a  sense  of  suffocation,  thirst,  tetanic 
spasms,  usually  opisthotonos,  sometimes  emprosthotonos,  occasionally  vomiting, 
contraction  of  the  pupils  during  the  spasms,  and  death  either  by  asphyxia  during 
a  paroxysm,  or  by  exhaustion  during  a  remission.  The  symptoms  appear  in 
from  a  few  minutes  to  an  hour  after  taking  the  poison,  usually  in  less  than 
twenty  minutes;  and  death  in  from  five  minutes  to  six  hours,  usually  within 
two  hours.  Death  has  been  caused  by  14  grain,  and  recovery  has  followed  the 
taking  of  20  grains. 

The  treatment  should  consist  in  bringing  the  patient  under  the  influence 
of  chloral  hydrate  or  of  chloroform,  and  then  washing  out  the  stomach.  The 
patient  should  be  kept  as  quiet  as  possible,  as  the  slightest  unexpected  irritation 
will  produce  a  spasm. 

Strychnine  is  one  of  the  most  stable  of  the  alkaloids,  and  may  remain  for 
a  long  time  in  contact  with  putrefying  organic  matter  without  suffering  de- 
composition. 

Brucine — C23H26N204+4Aq — 394+72  —  accompanies  strychnine. 
It  forms  oblique  rhomboidal  prisms,  which  lose  their  Aq  in  dry  air. 
Sparingly  soluble  in  H20,  readily  soluble  in  alcohol,  chloroform,  and 
amyl  alcohol;  intensely  bitter.  It  is  a  powerful  base  and  most  of 
its  salts  are  soluble  and  crystalline.  Its  action  on  the  economy  is 
similar  to  that  of  strychnine,  but  much  less  energetic. 

ANALYTICAL  CHARACTERS. — (1)  Concentrated  HN03  colors  it 
bright  red,  soon  passing  to  yellow;  stannous  chloride,  or  colorless 
NH4HS,  changes  the  red  color  to  violet.  (2)  Chlorine-water,  or  Cl, 
colors  brucine  bright  red,  changed  to  yellowish-brown  by  NH4OH. 

Curarine — C36H35N(?) — is  an  alkaloid  obtainable  from  the  South 
American  arrow-poison,  curare,  or  woorara.  It  crystallizes  in  four- 
sided,  colorless  prisms,  which  are  hygroscopic,  faintly  alkaline,  and 
intensely  bitter. 

Curarine  dissolves  in  H2S04,  forming  a  pale-violet  solution,  which 
slowly  changes  to  red.  If  a  crystal  of  potassium  dichromate  is 
drawn  through  the  H2S04  solution,  it  is  followed  by  a  violet  colora- 
tion, which  differs  from  the  similar  color  obtained  with  strychnine 
under  similar  circumstances,  in  being  more  permanent,  and  in  the 
absence  of  the  following  pink  and  yellow  tints. 

Isoquinoline  and  Phenanthrene  Alkaloids. — The  opium,  hydrastis, 
berberis  and  corydalis  alkaloids  are  included  in  these  groups.  Of  the 
opium  alkaloids,  papaverine,  narcotine  and  narceme  are  certainly 
derivatives  of  isoquinoline.  Morphine  and  codeine,  on  the  other  hand, 
do  not  contain  the  isoquinoline  nucleus,  but  a  phenanthrene  nucleus 
having  a  nitrogen-containing  ring  condensed  upon  it.  But  until 
the  constitution  of  these  two  alkaloids  is  established  with  more  com- 


434  TEXT-BOOK   OF   CHEMISTRY 

pleteness  it  is  not  desirable  to  separate  them  from  their  congeners 
(see  p.  437). 

Opium  Alkaloids. — Opium  is  the  dried  juice  obtained  by  making 
incisions  in  the  unripe  capsules  of  the  poppy,  Papaver  somniferum. 
It  is  of  exceeding  complex  composition,  and  contains  meconic,  lactic 
and  sulphuric  acids,  with  which  the  alkaloids  are  in  combination, 
meconine,  gum,  caoutchouc,  wax,  sugar,  resins,  etc.,  and  a  number 
of  alkaloids.  Some  twenty  alkaloids  have  been  obtained  from  opium, 
but  of  these  several  are  probably  produced  by  the  processes  of  ex- 
traction. The  most  important  of  the  natural  alkaloids  and  the 
average  percentage  in  which  they  exist  in  opium  of  good  quality 
are:  morphine,  10%;  narcotine,  6%;  papaverine,  1%,  codeine,  0.3%; 
narce'me,  0.2% ;  and  thebai'ne,  0.15%. 

Morphine— Morphina  (U.  S.  P.)—  C17H19N03+Aq— 285+18— 
crystallizes  in  colorless  prisms;  odorless,  but  very  bitter;  it  fuses  at 
120°,  losing  its  Aq.  More  strongly  heated,  it  swells  up,  becomes 
carbonized,  and  finally  burns.  It  is  soluble  in  1,000  pts.  of  cold  water, 
in  400  pts.  of  boiling  water ;  in  265  pts.  of  alcohol  of  90  per  cent,  at 
10°,  and  in  33  pts.  of  boiling  alcohol  of  the  same  strength;  in  373 
pts.  of  cold  amyl  alcohol,  much  more  soluble  in  the  same  liquid  warm ; 
almost  insoluble  in  aqueous  ether;  rather  more  soluble  in  alcoholic 
ether;  almost  insoluble  in  benzene;  soluble  in  2,500  pts.  of  chloro- 
form at  9  °,  and  in  45  pts.  at  £6  °.  All  the  solvents  dissolve  morphine 
more  readily  and  more  copiously  when  it  is  freshly  precipitated  from 
solutions  of  its  salts  than  when  it  has  become  crystalline. 

Morphine  combines  with  acids  to  form  crystallizable  salts,  of 
which  the  hydrochloride,  sulphate  and  acetate  are  used  in  medicine. 
If  morphine  is  heated  for  some  hours  with  excess  of  HC1,  under 
pressure,  to  150°,  it  loses  water,  and  is  converted  into  a  new  base — 
apomorphine,  C17H17N02. 

By  heating  together  acetic  anhydride  and  morphine,  acetylmor- 
phine,  C17H18(C2H30)N03,  and  diacetylmorphine,  C17H17(C2H30)2- 
N03,  are  formed.  The  latter  is  used  as  a  medicine  under  the  name 
heroine.  Similarly  substituted  butyryl-,  benzoyl-,  succinyl-,  cam- 
phoryl-,  methyl-,  and  ethyl-morphine,  are  also  known.  The  last 
named  is  used  medicinally  under  the  name  dionine. 

Morphine  is  readily  oxidized  and  a  strong  reducing  agent.  It 
reduces  the  salts  of  gold  and  silver  in  the  cold.  It  is  oxidized  by  at- 
mospheric oxygen  when  it  is  in  alkaline  solution,  as  well  as  by  nitrous 
acid,  potassium  permanganate,  potassium  ferricyanide,  or  ammoniacal 
cupric  sulphate,  with  the  formation  of  a  non-toxic  compound  which 
has  received  the  names,  pseudomorphine,  oxymorphine,  oxydimor- 
phine,  and  dehydromorphine  (C17N18N03)2,  whose  molecule  consists 
of  two  morphine  molecules,  united  with  loss  of  H2.  Morphine  sulphuric 
acid,  properly  morphylsulphuric  acid,  or  monomorphyl  sulpluitc, 
C18H18NO2.O.S03H,  corresponds  to  ethyl  sulphuric  acid  and  phenyl 


ALKALOIDS  435 

sulphuric  acid,  and  is  obtained  by  the  same  method  as  the  latter 
compound  from  morphine.  It  contains  H20  less  than  morphine  sul- 
phate, from  which  it  differs  in  that  the  acidyl  is  attached  through  a 
hydroxyl,  whereas  in  the  salt  it  is  attached  to  the  nitrogen.  When 
morphine  is  administered  it  appears  in  the  urine  as  pseudomorphine, 
and  also  probably  as  morphylsulphuric  acid,  both  of  which  are  non- 
toxic.  When  morphine  is  distilled  with  powdered  zinc,  the  principal 
product  of  the  reaction  is  phenanthrene,  accompanied  by  ammonia, 
trimethylamine,  pyrrole,  pyridine,  and  a  product  having  the  formula 
C17H11N,  probably  phenanthrene-quinoline. 

The  salts  of  morphine  are  crystalline.  The  acetate  is  a  white 
crystalline  powder,  soluble  in  12  parts  of  water,  which  decomposes 
on  exposure  to  air,  with  loss  of  acetic  acid.  The  chloride  is  less  sol- 
uble, but  more  permanent  than  the  acetate.  The  sulphate  is  the  form 
in  which  morphine  is  the  most  frequently  used  in  medicine.  It 
is  a  very  light,  crystalline,  feathery  powder;  odorless,  bitter,  and 
neutral  in  reaction.  It  dissolves  in  24  parts  of  water.  Its  solutions 
deposit  morphine  as  a  white  precipitate  on  addition  of  an  alkali.  The 
crystals  contain  5  Aq,  which  they  lose  at  130  °. 

ANALYTICAL  CHARACTERS. — (1)  It  is  colored  orange,  changing 
to  yellow,  by  HN03.  (2)  A  neutral  solution  of  a  morphine  salt 
gives  a  blue  color  with  neutral  solution  of  ferric  chloride.  (3)  A 
solution  of  molybdic  acid  in  H2S04  (Frohde's  reagent)  gives  with 
morphine  a  violet  color,  changing  to  blue,  dirty  green,  and  faint 
pink.  Water  discharges  the  color.  (4)  Take  two  test-tubes.  Into 
one  (a)  put  the  solution  of  morphine,  into  the  other  (6)  an  equal 
bulk  of  H20.  Add  to  each  a  granule  of  iodic  acid  and  agitate; 
a  becomes  yellow  or  brown,  b  remains  colorless.  To  each  add  a 
small  drop  of  chloroform  and  agitate:  the  CHC13  in  a  is  colored 
violet,  that  in  b  remains  colorless.  Float  some  very  dilute  ammo- 
nium hydroxide  solution  on  the  surface  of  the  liquid  in  a;  a  brown 
band  is  formed  at  the  junction  of  the  layers.  (5)  Moisten  the  solid 
material  with  HC1  to  which  a  small  quantity  of  H2S04  has  been 
added,  and  heat  in  an  air  oven  at  110°  until  HC1  is  expelled:  a  violet- 
colored  liquid  residue  remains.  Add  to  this  a  drop  or  two  of  water 
containing  a  little  HC1,  and  neutralize  with  powdered  sodium  bicar- 
bonate in  slight  excess:  a  pink  or  rose  color  is  produced,  most  dis- 
tinctly visible  on  the  bubbles.  Add  a  drop  of  water  and  a  drop  or  two 
of  alcoholic  solution  of  iodine:  a  green  color  is  developed.  This  re- 
action, known  as  the  Pellagri  test,  is  based  upon  the  conversion  of 
morphine  into  apomorphine,  and  consequently  reacts  with  that 
alkaloid.  (6)  Moisten  the  solid  with  concentrated  H2S04,  and  heat 
cautiously  until  white  fumes  begin  to  be  given  off,  cool  and  touch  the 
liquid  with  a  glass  rod  moistened  with  dilute  HN03:  a  fine  blue- 
violet  color,  changing  to  red  and  then  to  orange.  If  the  H2S04  con- 
tains oxides  of  nitrogen,  as  it  usually  does,  a  violet  tinge  will  be  pro- 


436  TEXT-BOOK   OF    CHEMISTRY 

duced  before  addition  of  HN03,  but  then  becomes  much  more  intense. 
This  reaction,  known  as  the  Husemann,  may  be  applied  by  allowing 
the  solid  to  remain  in  contact  with  H2SO4  for  fifteen  to  eighteen 
hours  in  place  of  heating.  (7)  Marquis'  reagent  (3  cc.  concentrated 
H2S04+2gtt.  formaline)  gives  a  brilliant  red-violet  color.  These  are 
the  most  important  tests  for  morphine,  and  affirmative  results  with  all 
of  them  prove  the  presence  of  that  alkaloid.  There  are  many  others. 

Codeine— Codeina  (U.  S.  P.)—  C18H21N03+Aq— 299+18— crys- 
tallizes in  large  rhombic  prisms,  or  from  ether,  without  Aq,  in  octa- 
hedra;  bitter;  soluble  in  80  pts.  cold  water;  17  pts.  boiling  water; 
very  soluble  in  alcohol,  ether,  chloroform,  benzene;  almost  insoluble 
in  petroleum-ether. 

Codeine  is  the  methyl  ether  of  morphine,  or  its  superior  homo- 
logue,  and  resembles  that  alkaloid  in  some  of  its  reactions;  thus 
under  similar  circumstances  both  form  apomorphine ;  and  morphine 
may  be  converted  into  codeine  by  the  action  of  methyl  iodide  in  the 
presence  of  KOH.  Codeine,  however,  only  contains  one  OH  group, 
and  forms  a  monoacetyl  derivative  with  acetyl  chloride,  while  mor- 
phine produces  a  diacetyl  compound. 

Narceine  —  C23H27N08+2Aq — 463+36  —  crystallizes  in  bitter, 
prismatic  needles ;  sparingly  soluble  in  water,  alcohol,  and  amyl  alco- 
hol; insoluble  in  ether,  benzene,  and  petroleum-ether. 

Narcotine — C22H23N07 — 413 — crystallizes  in  transparent  prisms, 
almost  insoluble  in  water  and  in  petroleum-ether;  soluble  in  alcohol, 
ether,  benzene,  and  chloroform.  Its  salts  are  mostly  uncrystallizable, 
unstable,  and  readily  soluble  in  water  and  in  alcohol. 

Narcotine  is  decomposed  by  H20  at  140°,  by  dilute  H2S04,  or  by 
baryta,  with  formation  of  opianic  acid,  C10H1005,  and  hydrocotar- 
nine,  C12H15N03.  Reducing  agents  decompose  it  into  hydrocotarnine 
and  meconine,  C10H1004.  Oxidizing  agents  convert  it  into  opianic 
acid  and  cotarnine,  C12H13N03. 

Papaverine — C20H21N04 — crystallizes  in  prisms;  almost  insoluble 
in  water,  easily  soluble  in  chloroform  and  in  hot  alcohol.  It  is 
optically  inactive.  It  forms  a  colorless  solution  with  concentrated 
H2S04,  which  turns  dark-violet  when  heated.  Acetic  anhydride  has 
no  action  upon  it. 

Thebaine — Paramorphine — C19H21N03 — 311 — crystallizes  in  white 
plates;  tasteless  when  pure;  insoluble  in  water,  soluble  in  alcohol, 
ether  and  benzene. 

Apomorphine — C17H17N02 — is  used  hypodermically  as  an  emetic 
in  the  form  of  the  chloride.  It  is  obtained  by  sealing  morphine,  with 
an  excess  of  strong  HC1,  in  a  thick  glass  tube,  and  heating  the 
whole  to  140°  for  two  to  three  hours.  It  is  obtained  also  by  the  same 
process  from  codeine.  The  free  alkaloid  is  a  white,  amorphous  solid, 
difficultly  soluble  in  water.  The  chloride  forms  colorless,  shining 
crystals,  which  have  a  tendency  to  assume  a  greenish  tint  on  ex- 


ALKALOIDS 


437 


posure  to  light  and  air.    It  is  odorless,  bitter  and  neutral;  soluble 
in  6.8  parts  of  cold  water. 

Relations  and  Constitution  of  the  Opium  Alkaloids. — The  al- 
kaloids of  opium  may  be  arranged  in  two  groups:  (I)  Including 
those  which  are  strong  bases,  are  highly  poisonous,  and  contain  three 
or  four  atoms  of  oxygen;  (II)  those  which  are  weak  bases  and  con- 
tain four  to  nine  oxygen  atoms.  So  far  as  known,  the  alkaloids  of 
the  first  group  contain  the  phenanthrene-pyridine  nucleus,  while  those 
of  the  second  group  are  derivatives  of  isoquinoline.  The  six  prin- 
cipal alkaloids  above  mentioned  are  equally  divided  between  the  two 
groups : 

I.  II. 

Morphine    C17H19N03     Papaverine     C20H21NO4 

Codeine     C18H21N03     Narcotine     C22H23NO7 

ThebaTne     C19H21N03    Narcei'ne    C23H2TN08 

Papaverine  was  first  recognized  as  an  isoquinoline  derivative.  On 
oxidation  of  papaverine  by  potassium  permanganate,  papaveraldine, 
C20H19N05,  is  formed.  This,  on  fusion  with  caustic  potash,  yields 
veratric  acid,  which  is  3,  4-dimethoxy-benzoic  acid,  C6H3.COOH: 
(OCH3)2(3  4),  and  dimethoxy isoquinoline,  the  constitution  of  the  latter 
being  established  by  its  further  decomposition  into  metahemipinic 
acid  andtf-^-x-pyridine-tricarboxylic  acid.  The  relations  of  papa- 
verine and  its  products  of  decomposition  are  shown  by  the  following 
formulae : 

COOH  H 


HC        CH  H3CO— C        C— COOH 

HC        C— OCH3  H3CO— C        C— COOH 

V  V 

OCH3  H 

Veratric  acid,  Metahemipinic    acid, 

(3,  4-Dimethoxy -benzole  acid).  (4,  5-Dimethoxy-o-phthalic    acid). 

H 


/\\ 
N     HC        CH 


V  V 


/AN 

HOOC— C        CH 

HOOC— C        N 

\  // 
C 

COOH 


HC        C— OCH3 
C 

OCH3 

Papaverine,  (Tetramethoxy-benzyl-a-isoquinoline) . 


a-j8-y-Pyridine-tricarboxylic    acid. 


438  TEXT-BOOK   OF    CHEMISTRY 

Narcotine,  C22H23N07,  is  converted  by  oxidation  into  opianic  acid, 
C10H1005  (p.  436),  and  cotarnine,  C12H15N04.  By  hydrolysis  it  yields 
'opianic  acid  and  hydrocotarnine,  C12H15NO3  ;  and  by  reduction,  meco- 
nine,  C10H1004  (p.  436),  and  hydrocotarnine.  Narcotine,  therefore, 
contains  the  nuclei  of  opianic  acid,  or  of  meconine,  and  of  hydro- 
cotarnine. The  constitution  of  opianic  acid  is  known,  as  well  as 
that  of  its  reduction  product,  meconine,  but  that  of  hydrocotarnine 
is  not  completely  established.  It  is,  however,  a  derivative  of  iso- 
quinoline,  containing  one  of  the  three  methoxy  groups  (CH30)  which 
exist  in  narcotine,  and  a  bivalent  group  —  O.CH2.0  —  attached  to  the 
benzene  ring;  and  a  methyl  group,  united  to  the  N  atom  in  the 
pyridine  ring. 

Narcei'ne,  C23H27N08  is  formed  by  the  action  of  caustic  potash 
upon  narcotine  iodomethylate  :  C22H23N07.CH3I  +  KOH  =  KI+ 
C23H27N08.  Narce'ine  apparently  does  not  contain  an  isoquinoline 
grouping,  that  which  exists  in  narcotine  having  been  broken  in  the 
above  method  of  formation  in  such  manner  that  the  N  is  in  a  lateral 
chain  in  narceine. 

Morphine,  C17H19N03,  and  codeine,  C18H21N03,  are  closely  related. 
Codeine  is  produced  by  the  action  of  methyl  iodide  upon  morphine- 
potassium:  C17H18KN03+CH3I=KI+C17HJ8(CH3)N03.  It  is,  there- 
fore, methyl-morphine.  By  the  further  action  of  methyl  iodide  upon 
codeine  in  alcoholic  solution,  codeine  methyl  iodide,  C18H21N03  :CH3I, 
is  produced,  and  this,  when  warmed  with  KOH,  is  converted  into 
methyl-morphine  methine,  C17H19N03:CH.CH3.  The  last-named 
substance  is  decomposed  by  acetic  anhydride  into  methyldioxyphen- 
anthrene  and  oxethyl-dimethyl-amine  :  C17H19N03  :CH.CH3=C14- 

/OTT  '    *-'-H3 

H8  (  X  PIT  +  N  —  CH3  ;  and  other  morphine  and  codeine  deriva- 

*\O.CH8^      \CH2.CH2.OH 

tives  are  similarly  decomposed,  with  formation,  on  the  one  hand,  of  a 
non-nitrogenized  oxy-phenanthrene  compound,  and,  on  the  other,  an 
oxyamine  or  a  trialkyl-amine.  Upon  these  facts,  it  is  concluded,  that 
the  morphine  and  codeine  molecules  consist  of  an  oxyphenanthrene 

CH3 


/\ 

group,  upon  which  is  fused  a  nitrogenized  group,     2  ,          .    It  is  also 

H2C 
\  / 
O 

recognized  that  the  two  hydroxyls  are  in  the  same  phenanthrene  ring, 
and  that  one  of  them  is  phenolic,  the  other  alcoholic;  also  that  one 
methyl  group  is  attached  to  the  nitrogen  atom.  The  disposal  of  the 
hydrogen  and  hydroxyls  in  the  phenanthrene  nucleus  and  the  position 
of  attachment  of  the  nitrogenized  group  above  referred  to  remain 
undetermined.  Two  formulae  of  constitution  of  morphine  have  been 
proposed,  either  of  which  is  in  consonance  with  the  known  facts  : 


ALKALOIDS  439 

OH 


I 


OH 


/\\ 
HOHC         CH  /   \\ 


HOHC         CH 

C  || 

\   //  \  0—  HC         C 


H2C 

s 

C         CH2  \   //   \ 

H2C  C         i 

O         C         CH2  III 

'  \    /  \\  /  H2C  C         i 

H2C         C         C  \          /   \\   / 

C         CH 


H3C— N— HC        C 
H2C         C         CH 

\  /    \  //  H2C         CH 


N         C  \// 

I        !  c 

CH3     H  H 

(I)  (ID 

The  formula  of  codeine  is  derived  from  either  formula  by  substitu- 
tion of  CH3  for  H  in  the  phenolic  OH;  that  of  apomorphine  by 
removal  of  H20. 

Thebaine,  C19H21N03,  is  decomposed  by  acetic  anhydride  in  a 
manner  quite  analogous  to  the  decomposition  of  morphine,  above  re- 
ferred to,  but  yielding  a  dimethoxy-phenolic  derivative  of  phenan- 
threne,  called  thebaol,  and  methyl-oxethyl-amine :  C19H21N03+H20= 

/H 

(CH30)2C14H7.OH+N— CH3  .    Like  morphine  and  codeine,  it 

\  CH2.CH2.OH 

is  therefore  a  phenanthrene-pyridine  derivative. 

Toxicology  of  Opium  and  its  Derivatives. — Opium,  its  preparations  and 
the  alkaloids  obtained  from  it  are  all  active  poisons.  The  alkaloids  have  not 
all  the  same  action.  In  soporific  effects,  beginning  with  the  most  powerful, 
they  rank  thus:  narcotine,  morphine,  codeine;  in  tetanizing  action:  theba'iine, 
papaverine,  narcotine,  codeine,  morphine ;  in  toxic  action :  thebai'ne,  codeine, 
papaverine,  narce'ine,  morphine,  narcotine. 

The  symptoms  set  in  from  ten  minutes  to  three  hours,  exceptionally 
"  immediately,"  or  only  after  eighteen  hours.  They  are  divisible  into  three 
periods:  (1)  a  stage  of  excitement,  marked  by  great  physical  activity,  loquacity 
and  imaginative  power ;  is  of  short  duration ;  longest  in  opium  habitues,  absent 
with  large  doses;  (2)  a  period  of  sopor,  in  which  there  are  diminished  sensi- 
bility, weariness,  contracted  pupils,  pale  face,  livid  lips,  drowsiness,  increasing 
to  deep  sleep,  from  which,  however,  the  patient  may  be  roused,  and  when  so 
roused  is  coherent  in  speech.  This  stage  merges  insensibly  into  the  third, 
that  of  coma.  The  patient  can  no  longer  be  aroused,  even  by  violent  means. 
The  face  is  pale,  the  lips  cyanosed,  the  muscular  system  completely  relaxed, 
the  reflexes  abolished,  the  pupils  contracted  greatly,  and  insensible  to  light, 
the  pulse  slow,  irregular,  compressible,  and  finally  imperceptible,  the  res- 
piration more  and  more  infrequent,  stertorous,  shallow,  and  accompanied 
by  mucous  rales.  Retention  of  urine  begins  early  in  the  poisoning.  The  usual 
duration  of  a  fatal  poisoning  is  from  six  to  twenty-four  hours.  Deaths  have 
occurred  in  forty-five  minutes  and  in  three  days. 

The  minimum  lethal  dose  for  a  non-habituated  adult  is  probably  3  to  4 
grains.  Young  children  are  very  susceptible.  Tolerance  to  a  remarkable  degree 


440  TEXT-BOOK   OF   CHEMISTRY 

is  established  by  habit,  both  in  children  and  in  adults,  and  instances  are  re- 
ported in  which  50  to  60  grains  have  been  taken  daily,  without  toxic  effects, 
by  morphine  takers. 

The  treatment  should  consist  in  washing  out  the  stomach  with  a  dilute 
solution  of  potassium  permanganate,  leaving  about  500  cc.  in  the  stomach,  and 
in  maintaining  the  respiration.  In  the  first  or  second  stage  the  "  ambulatory 
treatment "  should  be  adopted  to  prevent,  if  possible,  the  establishment  of  the 
third  stage.  If  this  stage  develops,  the  main  reliance  is  to  be  placed  in  main- 
taining the  respiration  by  artificial  methods,  until  the  poison  has  been  elimi- 
nated. Strong  coffee,  or  caffeine,  by  the  mouth  or  rectum  are  of  benefit.  The 
same  cannot  be  said  of  atropine.  The  urine  should  be  drawn  by  the  catheter. 

The  opiates  leave  no  post-mortem  lesions,  except  such  as  are  usually 
observed  after  death  from  asphyxia,  i.e.,  congestion  of  the  vessels  of  the  brain 
and  meninges,  and  of  the  lungs,  and  a  dark,  fluid  condition  of  the  blood. 

Alkaloids  of  unknown  constitution. — Of  the  numerous  alkaloids 
whose  constitution  is  insufficiently  known  to  permit  of  their  classifi- 
cation, only  a  few  can  be  here  briefly  considered: 

Alkaloids  of  the  Aconites. — The  different  species  of  Aconitum 
contain  probably  a  number  of  alkaloids,  but  our  knowledge  of  them 
is  as  yet  extremely  imperfect.  The  substances  described  as  aconitine, 
lycoctonine,  napelline  are  impure.  It  appears,  however,  that  the  prin- 
cipal alkaloids  of  Aconitum  napellus  and  of  A.  ferox,  although  differ- 
ing from  each  other,  are  both  compounds  formed  by  the  union  of 
aconine,  C25H41N09,  with  the  radical  benzoic  acid  in  the  former 
and  with  that  of  veratric  acid  in  the  latter. 

Aconitine— Acetylbenzoyl-aconiner—  C25H3?(CHS.CO)  (C6H5.CO) 
N09 — the  principal  alkaloid  of  A.  napellus,  is  a  crystalline  solid, 
almost  insoluble  in  water,  and  very  bitter.  It  is  decomposed  by  H20 
at  140°  and  by  KOH  into  aconine  and  acetic  and  benzoic  acids.  It 
is  very  poisonous. 

Pseudo-aconitine — C36H49N012 — occurs  in  A.  ferox.  It  is  a  crys- 
talline solid,  having  a  burning  taste,  and  is  extremely  poisonous.  On 
decomposition  by  H20  at  140  °  it  yields  aconine  veratric  acid. 

Japaconitine — C66H88N2021 — has  been  obtained  from  the  root  of 
A.  japanicum,  and  is  a  crystalline  solid  which  is  decomposed  by 
alkalies  into  benzoic  acid  and  japaconine,  C2fiH4iN010. 

The  color  reactions  described  as  characteristic  of  "aconitine" 
are  not  due  to  the  alkaloid. 

TOXICOLOGY. — Aconite  and  "aconitine"  have  been  the  agents  used  in  quite 
a  number  of  homicidal  poisonings. 

The  symptoms  usually  manifest  themselves  within  a  few  minutes;  some- 
times are  delayed  for  an  hour.  There  is  numbness  and  tingling,  first  of  the 
mouth  and  fauces,  later  becoming  general.  There  is  a  sense  of  dryness  and  of 
constriction  in  the  throat.  Persistent  vomiting  usually  occurs,  but  is  absent 
in  some  cases.  There  is  diminished  sensibility,  with  numbness,  great  muscular 
feebleness,  giddiness,  loss  of  speech,  irregularity  and  failure  of  the  heart's  action. 
Death  may  result  from  shock  if  a  large  dose  of  the  alkaloid  be  taken,  but  more 
usually  it  is  by  syncope. 

The  treatment  should  be  directed  to  the  removal  of  unabsorbed  poison  by 


ALKALOIDS  441 

the  stomach-pump,  and  washing  out  of  the  stomach  with  infusion  of  tea  holding 
powdered  charcoal  in  suspension.     Stimulants  should  be  freely  administered. 

Alkaloids  from  other  Sources. — Ergotine — C50H52N203 — and 
Ecboline  are  two  brown,  amorphous,  faintly  bitter,  and  alkaline 
alkaloids  obtained  from  ergot.  They  are  readily  soluble  in  water  and 
form  amorphous  salts.  The  medicinal  preparations  known  as  ergotine 
are  not  the  pure  alkaloid. 

Colchicine— C17H19N05— occurs  in  all  portions  of  Colchicum 
autumnale  and  other  members  of  the  same  genus.  It  is  a  yellowish- 
white,  gummy,  amorphous  substance,  having  a  faintly  aromatic  odor 
and  a  persistently  bitter  taste.  It  is  slowly  but  completely  soluble  in 
water,  forming  faintly  acid  solutions.  It  forms  salts  which  are,  how- 
ever, very  unstable. 

Concentrated  HN03,  or,  preferably,  a  mixture  of  H2S04,  and 
NaN03,  colors  colchicine  blue-violet.  If  the  solution  is  then  diluted 
with  H20,  it  becomes  yellow,  and  on  addition  of  NaOH  solution, 
brick-red. 

Veratrine— Veratrina  (U.  S.  P.)— C32H52N208— occurs  in  Vera- 
trum  officinale=Asagrcea  officinalis,  accompanied  by  Sabadilline — 
C20H26N205 — Jervine — C30H46N203 — and  other  alkaloids.  The  sub- 
stance to  which  the  name  Veratrina,  U.  S.  P.,  applies  is  not  the  pure 
alkaloid,  but  a  mixture  of  those  occurring  in  the  plant. 

Concentrated  H2S04  dissolves  veratrine,  forming  a  yellow  solu- 
tion, turning  orange  in  a  few  moments,  and  then,  in  about  half  an 
hour,  bright  carmine-red.  Concentrated  HC1  forms  a  colorless  solu- 
tion with  veratrine,  which  turns  dark-red  when  cautiously  heated. 

Physostigmine — Eserine — C15H21N302 — is  an  alkaloid  existing  in 
the  Calabar  bean,  Physostigma  venenosum.  It  is  a  colorless,  amor- 
phous solid,  odorless  and  tasteless,  alkaline  and  difficultly  soluble  in 
water.  It  neutralizes  acids  completely,  with  formation  of  tasteless 
salts.  Its  salicylate — Physostigminae  salicylas,  U.  S.  P. — forms  short, 
colorless,  prismatic  crystals,  sparingly  soluble  in  water. 

Concentrated  H2S04  forms  a  yellow  solution  with  physostigmine 
or  its  salts,  which  soon  turns  olive-green.  Concentrated  HN03  forms 
with  it  a  yellow  solution.  If  a  solution  of  the  alkaloid  in  H2S04  is 
neutralized  with  NH4OH,  and  the  mixture  warmed,  it  is  gradually 
colored  red,  reddish-yellow,  green,  and  blue. 

Emetine — C28H40N205 — an  alkaloid  existing  in  ipecacuanha  which 
crystallizes  in  colorless  needles  or  tabular  crystals,  slightly  bitter  and 
acrid;  odorless,  and  sparingly  soluble  in  water. 

It  dissolves  in  concentrated  H2S04,  forming  a  green  solution, 
which  gradually  changes  to  yellow.  With  Frohde's  reagent  it  gives 
a  red  color,  which  soon  changes  to  yellowish-green  and  then  to  green. 


442  TEXT-BOOK   OF   CHEMISTRY 


PTOMAINES,  LEUCOMAINES  AND  TOXINES. 

The  name  ptomaine,  derived  from  Trry/za  ("that  which  has  fallen,"  i.e.,  a 
corpse),  was  first  suggested  by  Selmi  in  1878  to  apply  to  a  substance,  or  class 
of  substances,  first  distinctly  recognized,  although  not  isolated,  by  him,  which 
are  produced  by  saprophytic  bacteria  from  proteins  during  putrefaction.  The 
ptomaines  are  sometimes  referred  to  as  "  animal  alkaloids,"  a  term  which  is  mis- 
leading, as  they  are  produced  from  vegetable  as  well  as  from  animal  proteins,  and 
but  few  of  them  are  alkaloids  in  the  present  acceptation  of  the  term  (p.  419). 
The  great  majority,  and  those  the  best  known,  are  monamines,  diamines,  guani- 
dines,  hydramines,  betai'nes,  or  amido  acids.  The  term  "  ptomaines  "  does  not 
therefore  apply  to  the  members  of  a  distinct  class  of  chemical  compounds,  but  to 
the  bacterial  origin  of  substances  belonging  to  several  distinct  chemical  classes 
and  also  obtainable  by  other  methods,  having  in  common  only  the  two  qualities 
that  they  are  basic  and  contain  nitrogen.  But  some  ptomaines  are  true  alkaloids. 
Some  of  the  superior  homologues  of  pyridine  are  putrid  products.  A  base 
C8HnN,  isomeric  with  collidine,  formed  during  putrefaction  of  jelly-fish,  on 
oxidation  yields  nicotinic  acid,  C5H4N(COOH),  which  is  also  similarly  produced 
from  nicotine  (p.  423),  and  also  forms  a  chloroplatinate  and  an  iodomethylate 
which  have  the  characteristic  properties  of  the  like  compounds  produced  from 
the  pyridine  bases  and  vegetable  alkaloids.  Other  basic  substances  obtained 
from  brown  cod-liver  oil,  and  probably  formed  by  a  modified  putrefaction,  are 
hydropyridine  derivatives.  Among  these  are  a  dihydrolutidine,  C7HnN,  a 
dihydrocollidine,  CsHiSN,  and  a  complex  hydropyridic  oxyacid,  called  morrhuic 
acid,  HO.C3H5N.C3H6.COOH.  Indole  and  skatole,  products  of  putrefaction,  also 
come  within  the  definition  of  alkaloids. 

A  ptomaine  may  be  defined  as  a  basic  compound,  containing  nitrogen, 
produced  from  protein  material  by  the  bacteria  which  cause  putrefaction. 

Owing  to  the  wide  variationc  in  the  chemical  constitution  of  the  ptomaines, 
they  possess  no  characters  by  which  they  can  be  distinguished  as  a  class.  Some 
are  strongly  alkaline  and  basic,  others  only  feebly  so.  Some  are  liquid,  oily 
and  volatile,  others  fixed  and  crystalline.  Some  are  very  prone  to  oxidation, 
and  are  active  reducing  agents,  others  are  quite  stable.  For  the  same  reason, 
no  analytical  method  is  possible  by  which  vegetable  alkaloids  and  ptomaines 
can  be  separated  from  each  other  en  masse,  nor  are  any  reactions  known  to  which 
all  ptomaines  respond  while  vegetable  alkaloids  do  not,  or  the  reverse;  nor  are 
such  reactions  to  be  expected.  Certain  classes  of  ptomaines  may  be  identified 
or  separated  from  vegetable  alkaloids,  but  not  all.  Thus  those  which  arc 
diamines  may  be  separated  by  formation  of  their  benzoyl  derivatives,  but  only 
a  few  ptomaines  are  diamines.  Those  ptomatnes  which  are  reducing  agents  ^ive 
a  blue  color  with  a  mixture  of  ferric  chloride  and  potassium  ferricyanide  but 
all  ptomaines  do  not  reduce,  and  some  vegetable  alkaloids,  such  as  morphine 
and  veratrine,  do.  It  was  feared  that  the  existence  of  ptomaines,  whoso  forma- 
tion begins  shortly  after  death,  and  also  occurs  during  life,  might  render  flu- 
detection  of  vegetable  poisons  in  the  cadaver  impossible.  Such  fears  were  by 
no  means  groundless,  as  thero  is  abundant  evidence  that  ptomaTnos  have  boon 
mistaken  for  vegetable  alkaloids  in  chemico-lepral  analyses.  It  is.  however, 
possible  to  positively  and  certainly  predicate  the  existence  or  non-existence  in  a 
cadaver  of  a  given  vegetable  alkaloid,  provided  it  has  a  sufficient  number  of 
characteri/inj;  reactions,  hut.  it  can  only  be  done  after  a  thorough  and  con- 
scientious examination  by  all  physiological  and  chemical  reactions. 

Leucomames  are  nitrogenous,  basic  substances  which  are  produced 
in  the  bodies  of  animals  during  life  as  results  of  normal  chemical  processes. 
They  ;«n-  excreted  in  hc;il1h.  and  if  retained  exert  deleterious  actions,  more  or 
less  intense.  The  xanthine,  or  purine,  liases  and  those  of  the  creatine  group  are 


PTOMAINES,   LEUCOMAINES,   AND   TOXINES  443 

leucomai'nes,  and  others  occur  in  the  urine.  But,  as  some  leucomalnes,  such  as 
choline,  tyrosine,  and  betaine,  are  also  ptomaines,  being  produced  by  saprophytic 
bacteria.,  the  line  of  distinction  cannot  be  sharply  drawn. 

Toxines. — The  name  "toxine"  was  first  used  by  Brieger,  and  by  him  applied 
to  poisonous  ptomaines  and  other  toxic,  basic,  nitrogenous  substances,  obtained 
from  the  culture  media  of  pathogenic  bacteria  or  from  animal  organisms.  Such 
are  the  four  basic  substances  obtained  from  the  culture  media  of  the  tetanus 
bacillus:  Tetanine,  C13HnN2O4,  a  yellow,  strongly  alkaline  syrup;  Tetanotoxine, 
C5HnN  (  ? ) ,  a  volatile  oil ;  Spasmotoxine,  and  another  unnamed  base  of  un- 
determined composition,  all  of  which  form  deliquescent  hydrochlorides,  and 
very  soluble,  crystalline  platinochlorides.  These  bases,  when  injected  into 
animals,  cause  clonic  or  tonic  convulsions  of  great  intensity,  terminating  in 
death.  But  it  has  been  shown  that  the  cultures  from  which  these  basic  sub- 
stances are  obtainable,  after  filtration  through  porcelain,  are  vastly  more  toxic 
than  the  combined  bases.  These  therefore  can  only  constitute  a  small  fraction 
of  the  active  material  produced  by  the  bacilli,  and  the  more  virulent,  non-basic 
product  is  a  toxine  in  the  more  modern  sense. 

In  this  latter  sense  the  toxines  are  poisonous  substances  of  unknown  chemi- 
cal composition  produced  by  bacteria  or  other  cells.  They  are  not  products  of 
decomposition  of  the  proteins,  as  are  the  ptomaines,  but  synthetic  products, 
secretions,  as  it  were,  of  the  bacteria.  They  are  not  all  members  of  the  same 
chemical  class.  Some,  the  extracellular  toxines,  so  called  because  they  pass 
in  great  part  into  the  culture  media,  have  many  resemblances  to  the  albumoses. 
They  are  non-crystalline,  soluble  in  water,  and  dialysable,  are  precipitated  by 
alcohol  and  by  ammonium  sulphate,  and  lose  their  virulence  when  heated.  The 
toxines  of  diphtheria  and  tetanus  belong  to  this  class.  But  little  is  known  of 
the  properties  of  the  intracellular  toxines,  which  are  largely  retained  in  the 
bacterial  cells  until  these  are  destroyed,  except  that  they  do  not  dialyse,  and 
are  more  resistant  to  heat  than  the  extracellular  toxines.  The  toxines  of  typhoid, 
tubercle  and  glanders  belong  to  this  second  class. 

The  toxalbumins  are  substances  obtained  from  certain  seeds  or  secreted 
by  animals,  which  are  highly  toxic,  and  have  the  general  properties  of  albumoses 
or  of  globulins.  They  therefore  differ  from  the  toxines  solely  in  that  they  are 
not  of  bacterial  origin,  and,  furthermore,  they  resemble  bacterial  poisons  more 
closely  than  vegetable  alkaloids  in  their  actions,  particularly  in  the  latent 
period  preceding  the  manifestation  of  their  effects. 

Putrefaction  is  the  decomposition  of  dead  protein  material  under  the  in- 
fluence of  certain  bacteria,  attended  by  the  evolution  of  more  or  less  fetid 
products.  In  order  that  it  may  occur,  certain  conditions  are  necessary:  (1)  The 
presence  of  living  bacteria,  or  of  their  germs;  (2)  the  presence  of  moisture; 
(3)  a  temperature  between  5°  and  90°;  (4)  an  atmospheric  condition  suitable 
to  the  growth  of  the  bacteria.  Some  of  the  several  species  of  bacteria  which 
cause  putrefaction  are  aerobic,  i.e.,  require  the  presence  of  air  for  their  de- 
velopment, while  others  are  anaerobic,  i.e.,  they  thrive  best  in  the  absence  of 
oxygen.  Proteins  which  have  been  deprived  of  moisture,  either  by  drying  or 
by  the  action  of  dehydrating  agents,  such  as  strong  alcohol,  do  not  enter 
into  putrefaction  unless  water  is  supplied  to  them,  when  the  process  proceeds 
as  usual.  The  temperature  most  favorable  to  putrefaction  is  about  40°.  High 
or  low  temperatures  arrest  putrefaction  or  prevent  it,  the  former,  if  sufficiently 
high,  permanently  (if  the  material  is  protected  from  new  bacteria)  by  de- 
stroying the  vitality  of  the  bacteria;  the  latter,  even  if  extreme,  only  tempo- 
rarily, and  so  long  as  the  low  temperature  is  maintained. 

Putrefaction  may,  therefore,  be  prevented  either  (1)  by  the  action  of 
agents  or  substances  which  interfere  with  the  development  of  bacteria  (germi- 
cides and  antiseptics)  ;  (2)  by  the  exclusion  of  air;  (3)  by  the  exclusion  of 
water;  (4)  by  a  temperature  below  5°  or  above  90°. 


444  TEXT-BOOK   OF   CHEMISTRY 

Putrefaction  is  attended  by  the  breaking  down  and  liquefaction  of  the 
material  if  it  is  solid;  or  its  clouding  and  the  formation  of  a  scum  upon  the 
surface  if  it  is  liquid.  The  products  of  putrefaction  vary  with  the  conditions 
under  which  it  occurs.  The  most  prominent  are:  (1)  inorganic  products  such 
as  N,  H,  H2S,  NH3,  and  simple  organic  compounds,  such  as  CO,  and  hydro- 
carbons; (2)  acids  of  the  fatty  series  in  great  abundance,  and  acids  of  the 
oxalic  and  lactic  series;  (3)  non-aromatic  monamines  and  diamines,  such  as 
trimethylamine,  putrescine,  and  certain  of  the  ptomaines;  (4)  aromatic  prod- 
ucts, among  which  are:  (a)  phenols,  such  as  tyrosine,  oxyaromatic  acids, 
phenol,  and  cresol;  (6)  phenylic  derivatives,  such  as  phenyl  acetic  and  phenyl 
propionic  acids;  (c)  indole,  skatole,  skatole-carbonic  acid,  etc.;  (d)  ptomaines 
of  undetermined  constitution,  but  belonging  to  the  aromatic  series;  pyridine 
derivatives. 

Under  certain  imperfectly  defined  conditions  buried  protein  material  does 
not  undergo  ordinary  putrefaction,  but  is  converted  into  a  substance  resembling 
tallow,  and  called  adipocere,  which  consists  chiefly  of  ammonium  palmitiitc, 
stearate  and  oleate,  calcium  phosphate  and  carbonate,  and  an  undetermined 
nitrogenous  substance. 

Germicides  are  substances  or  agents  which  destroy  bacteria  and  their 
germs.  Mercuric  chloride  and  heat  are  germicides. 

Antiseptics  are  substances  which  prevent  or  restrain  putrefaction. 
Antiseptics  are  either  germicides,  which  prevent  putrefaction  by  destroying 
the  organisms  which  cause  it,  or  are  agents,  which  interfere  with  the  develop- 
ment of  these  organisms  without  destroying  their  vitality.  The  salts  of 
aluminium  are  antiseptic  by  reason  of  their  chemical  action  on  the  proteins, 
although  their  germicidal  powers  are  slight. 

Deodorizers,  or  air  purifiers,  are  substances  which  destroy  the  odorous 
products  of  putrefaction. 

Disinfectants  are  substances  which  restrain  infectious  diseases  by  de- 
stroying or  removing  their  specific  poisons. 


APPENDIX 


TABLE  OF   SOLUBILITIES 

FRESENIUS. 

W  or  w  =  soluble  in  H20.    A  or  a  =  insoluble  in  H20 ;  soluble  in 
HC1,  HN03,  or  aqua  regia.     I  or  i  =  insoluble  in  H20  and  acids. 
W-A  =  sparingly   soluble   in    H20,    but   soluble   in   acids.    W-I  = 
sparingly  soluble  in  H20  and  acids.    A-I  =  insoluble  in  H20,  spar- 
ingly soluble  in  acids.    Capitals  indicate  common  substances. 


Aluminium. 

Ammonium. 

Antimony. 

Barium. 

Bismuth. 

Cadmium. 

Calcium. 

Chromium. 

Cobalt. 

M 

O> 

! 

Ferrous. 

« 
*C 

1 

Acetate  

W 

W 

W 

w 

w 

W 

w 

w 

\Y 

W 

Arsenate  
Arsenite  

a 

w 
w 

a 
a 

a 
a 

a 

a 

a 
a 

a 

a 
a 

a 
A 

a 
a 

a 
a 

Benzoate  

w 

w 

w 

W 

w 

a 

w 

Borate  

a 

w 

a 

a 

w-a 

a 

a 

a 

a 

Bromide 

W 

w 

w-a 

w-i 

Carbonate 

a 

W 

A 

A 

a 

A 

a 

A 

A 

A 

a 

Chlorate  

W 

w 

w 

w 

w 

w 

w 

w 

Chloride 

W3 

W-A* 

W 

W-A10 

W 

W 

\V-I 

W 

Chromate  .... 

w 

a 

a 

a 

a 

w-a 

a 

a 

w 

w 

Citrate  

w 

w 

a 

a 

w-a 

w 

\v 

w 

Cyanide  

w 

w-a 

a 

w 

a 

a-i 

a 

a-i 

Ferricyanide  .  . 

Vf 

w 

i 

I 

w 

Ferrocyanide  . 

w 

w-a 

w 

j 

j 

i 

T 

Fluoride   .... 

W 

w 

a-i 

w 

w-a 

A 

w 

•\V-ll 

a 

\v-a 

Formate  

w 

w 

w 

w 

AV 

w 

w 

w 

w 

w 

w 

Hydrate 

A 

W 

A 

VV 

a 

a 

\\  -  \ 

A 

A 

a 

a 

A 

Iodide 

W 

w 

a 

W 

w 

w 

w 

\v 

W 

Malate             . 

w 

w 

w-a 

Nitrate  

w 

W 

W 

W11 

w 

w 

W 

\Y 

\V 

W 

W 

Oxalate  

a 

W 

a 

a 

a 

a 

A 

w-a 

A 

a 

a 

a 

Oxide  
Phosphate 
Silicate 

A-] 
a 
A-I 

w» 

a7 
w-a 

W 

w-a 
a 

a 
a 

a 
a 
a 

W-A 
W-A 

£t 

A-I 
a 
a 

A 

a 
a 

A 
a 
a 

a 
a 
a 

A 

a 
a 

\v-a 

w 

w-a 

w 

W-'l 

\v-;i 

\v 

Sulphate  

W1 

W4 

a 

A 

w 

W 

W-I 

W-A12 

W" 

W 

W 

W 

Sulphide  

a 

w 

A8 

W 

a 

A 

W-A 

a-i 

a 

A 

A 

A 

Tartrate  

w 

w» 

a9 

a 

a 

w-a 

a 

\v 

w 

\v 

\v-a 

W*' 

1(A12)(NH4)2(S04)4=W;  (A12)K0(S04)4=W.  2As(NH4)Cl4= 
W;  Pt(NH4)Clr)=W-I.3HNa(NH4)P04=W;  Mg(NH4)P04=A.  4Fe- 
(NH4)2(S04)2=W;  Cu(NH4),(S04),=W.  5C4H4Or,K(NH4)=W. 
6SbOCl=A.  7Sb203=soluble  in  HC1,  not  in  HNO,.  8Sb.,S,=sol.  in 
hot  HC1,  slightly  in  HN03.  8C4H4OfiK(SbO)=W.  10BiOCl=A. 
n(BiO)  NO,=A.  12(Cr2)K0(S04)4=W.  13CoS=easily  sol.  in  HN03, 
very  slowly  in  HC1.  u(C4H406)4(Fe2)K1=:W. 


SOLUBILITIES  447 

TABLE  OF  SOLUBILITIES.— Continued. 

FRESENIUS. 

W  or  w  =  soluble  in  H20.  A  or  a  —  insoluble  in  H20 ;  soluble  in 
HC1,  HN03,  or  aqua  regia.  I  or  i  =  insoluble  in  H20  and  acids. 
W-A  =  sparingly  soluble  in  H20,  but  soluble  in  acids.  W-I  = 
sparingly  soluble  in  H20  and  acids.  A-I  =  insoluble  in  H20,  spar- 
ingly soluble  in  acids.  Capitals  indicate  common  substances. 


s 

E 
1 

5 

w 
a 
a 
w 
w-a 
w 
A 
w 
W 
w 
w 
w 
w 
w 
a-i 
w 
A 
w 
w 
w 
a 
A 
a3 
a 
w 
W 
a 
w-a 

1 
1 

W 

a 
a 
w 
a 
w 
A 
w 
W 
w 
a 
a 
i 
a 
a 
w 
a 
w 
w 
w 
w-a 
A15 
a 
a 
w 
W 
a 
w-a 

P  jo  p  |  Mercurous. 

Mercuric. 

w 
a 
a 

a 
w 
A 
w 
W 
a 
w 
a-i 
i 
i 
w-a 
w 
a 
w 

W 
a 
A 

a 
a 
w 
W 

A19 
a 

Potassium. 

i 

Sodium. 

Strontium. 

p  P  ^  Stannous. 

1 

w 
a 

G 
N 

Acetate  

w 

a 
a 
a 
a 
w-i 
A 
w 
W-I 
A-I 
a 
a 
w-a 
a 
a 
w-a 
a 
W-A 
w-a 
W 
a 
A 
a 
a 
a 
A-I 
A 
a 

w 
a 
a 
w-a 

W 
W 
w 
w 
W 
W 
W 
W 
W20 
W 
w 
W 
W 
W 
w 
w 
W 
W 
w 
W 
W 

w 

w 
W 
w 
W12 
W 
W 

w 
a 
a 
w-a 
a 
a 
a 
w 
I 
a 
a 
i 
i 
i 
w 
w 

i 
w-a 
W 
a 
a 
a 

a 
W-A 

a21 
a 

W 
W 
w 
w 
W 
W 
W 
w 
W 
w 
W 
w 
w 
w 
w 
w 
W 
w 
w 
W 
W 
W 
W 
W 
w 
W 
W 
w 

w 
a 
a 

W 

Arsenate  
Arsenite 

Benzoate 

Borate  

a 
w 
A 
w 
W 
w-a 
a 
w 

a 

a 
w 
A 
w 
W 
w 
w-a 
a 
a 
a-i 
w-a 
w 
a 
w 
w 
w 
a 
A 
a 
a 
w-a 
W 
A23 
a 

Bromide  
Carbonate  
Chlorate  
Chloride 

a-i 
a 
w 
A-I 
a 
a 

w 
a 
w 
W18 
w-a 
w-a 
W 

w 
W 
a 

"w* 

Chromate  
Citrate 

Cyanide  

.... 

Ferrocyanide  
Fluoride  
Formate  

w 
a-i 
w 
w 
w 
w 
W 
a 
W 
a 
a 
w-a 
I 
w 
a 

w 

w-a 
w 

w 
w 
a 
w 
w 

w 

a 
w 
w 

Hydrate 

Iodide      

A 

a 
W 
a 
A 

a 

A 
w-a 
W 
a 
A 
a 

Malate  

Nitrate  
Oxalate  

a 
a 
a 

w 
A-I 
a 

Oxide 

Phosphate  
Silicate.        .... 
Succinate  

a 
w-a 
a 
w-a 

w-a 
W17 

A18 
a 

w 
a22 
a 

a 

A" 

Sulphate  

Sulphide  

Tartrate  

15Mn02=sol.  in  HC1 ;  insol.  in  HN03.  16Mercurammonium  chlo- 
ride=A.  17Basic  sulphate=A.  18HgS=insol.  in  HC1  and  in  HN03, 
sol.  in  aqua  regia.  19See  13.  ,20PtKCl5=W-A.  210nly  soluble  in 
HN03  22Sn  sulphides=sol.  in  hot  HC1;  oxidized,  not  dissolved,  by 
HNO3.  Sublimed  SnCl4  only  sol.  in  aq.  regia.  23Easily  sol.  in 
HN03,  difficultly  in  HC1. 

Au2S=insol.  in  HC1  and  in  HN03,  sol.  in  aq.  regia.  AuBr3, 
AuCl3,  and  Au(CN)3=w;  AuI3=a.  PtS2=insol.  in  HC1,  slightly  sol. 
in  hot  HN03;  sol.  in  aq.  regia.  PtBr4,  PtCl4,  Pt(CN)4,  Pt(N03)4, 
Pt(C204)2,  Pt(S04)2=w;  Pt02=a;PtI/=i. 


INDEX 


INDEX 


INDEX 


Absolute  temperature,   13. 

zero,   13. 

Absorption  of  gases,  11. 
Acetal,  233. 
Acetaldehyde,  229. 
Acetaldoxime,  320. 
Acetals,  232. 
Acetamide,  312. 
Acetanilide,  372. 
Acetates,  253. 
Acetol  salicylate,  358. 
Acetonamines,   319. 
Acetone,  234. 

diethylsuphone,   287. 

dimethylsulphone,  287. 
Acetonemia,  235. 
Acetones,   233. 
Acetonitrile,  305,  306,  313. 
Acetophenone,    355. 

oxime,  355. 

Acetophenyl  hydrazide,  381. 
Acetoxime,  320. 
Acetoximes,  320. 
Acetyl  benzene,  355. 

benzoylaconine,  440. 

chloride,  270. 

hydroxide,  252. 

morphine,  434. 
Acetylene,  329. 

series,  201,  329. 
Acetylide,  329. 
Achroodextrins,   246. 
Acid   (see  also  Acids). 

acetic,  252. 

acetoacetic,  266. 

acetohydroxamic,  301. 

acetylamidoacetic,  323. 

aconitic,  265. 

acrylic,   330,  331. 

allophanic,   317. 

amidoacetic,  323    (see  Glycocoll). 

amidobenzoic,  356. 

amidoformic,    313,    322    (see   Acid, 
Carbamic ) . 

amidoisobutylacetic,   325. 

amidovaleric,  325. 

amygdalic,  362. 
Acid  anhydrides,  269. 
Acid,   anilidoacetic,  375. 

anilindisulphonic,  371. 

anilpyroracemic,  376. 

anthranilic,  356,  374. 

antitartaric,  264. 

arachic,   256. 


Acid,  arsenic,  113,  115. 
arsenous,  113. 
auric,  129. 
barbituric,  404. 
benzenedicarboxylic,  357. 
benzenemonosulphonic,  366. 
benzene  sulphonic,  341. 
benzene  trisulphonic,  366. 
benzhydroxamic,  376. 
benzoic,   356. 
benzoylamidoacetic,  375   (see  Acid, 

hippuric ) . 
boracic,    124. 
boric,   124. 
butan,  253. 
butyric,  253. 
cacodylic,   327. 
cachoutannic,  360. 
caffeic,  360. 
caffetannic,  360. 
capric,  255. 
caprylic,  255. 
carbamic,  313. 
carbanilic,  375. 
carbazotic,  369. 
carbolic,  345   (see  Phenol), 
carbonic,   261. 
chelidonic,  397. 
chloric,  79. 
chromic,  131. 
cinchomeronic,  430. 
citraconic,  265. 
citric,  265. 
comenic,  397. 
cumic,  356. 
cyanic,  307. 
cyanuric,  307,  315. 
decylic,  255. 
dextrolactic,  262. 
dextrotartaric,  264. 
diacetic,  266. 
dialuric,  404. 
dichloracetic,  253. 
dichromic,   131. 
digallic,  360. 
dihydrocyanic,   310. 
dimethylacetic,  254. 
dinitronaphtholsulphonic,    387. 
dioxybenzoic,  359. 
dioxycinnamic,   360. 
dioxymalonic,  266. 
disulphanilic,  371. 
dithiocarbamic,  316. 
elai'dic,  332. 


451 


452 


INDEX 


Acid,  erythroglucic,  225. 

ethan,   252. 

ethidenelactic,   262. 

ethidenepropionic,  331. 

ethylacetic,  253. 

ethylenelactic,  263. 

ethylsulphonic,  277. 

ethylsulphuric,  268,  277. 

formic,  251. 

fulminic,  307. 

fulminuric,   308. 

fumaric,  332. 

furfurane  carboxylic,  392. 

gadinic,  282. 

gallic,  359. 

glucovanillic,  362. 

glucuronic,  266. 

glutaric,  259. 

glycerophosphoric,  281. 

glycolamic,  323. 

glycollic,  262. 

glycoluric,  318. 

glycosuric,  35!). 

glyoxalineamidopropionic,   396. 

glyoxylic,  265. 

graphitic,  125. 
Acid  halides,  aliphatic,  270. 

aromatic,  364. 
Acid,  hexahydro-tetroxybenzoic,  384. 

hippuric,  375. 

homogentisinic,  359. 

homoprotocatechuic,  359. 

hydantoic,  317,  318. 

hydracrylic,   263. 

hydrazoic,  97. 

hydriodic,  82. 

hydrobromic,   80. 

hydrochloric,  76. 

hydrochloroplatinic,    148. 

hydrocyanic,  303. 

hydrofluoric,  73. 

hydrofluosilicic,  127. 

hydronitroprussic,  310. 

hydrosulphurous,   89. 

hypobromous,  81. 

hypochlorous,  79. 

hyponitrous,   100. 

hypophosphoric,  109. 

hypophosphorous,  108. 

hyposulphurous,  89,  92. 

indoleacetic,  416. 

indoleamidopropionic,  416. 

indoxylic,  417. 

indoxylsulphuric,  417. 

iodic,  83. 

isethionic,  286. 

isobarbituric,  407. 

isobutyric,   254. 

isocyanic,  318. 

isodialuric,  407. 

isoplillialic,  :5f>7. 

isopropvlacctic.  254. 

isopropylbenzoic,  356. 


Acid,  isostrychnic,  432. 
isothiocyanic,   308. 
isovalcric,  254. 
itaconic,  265. 
lactic,  262. 
Ircvolactic,  263. 
laevotartaric,  264,  205. 
laevulinic,  347. 
lauric,  255. 
laurostearic,   255. 
lithic,  406. 
maleic,  332. 
malic,  263. 
malonic,  258. 
mannosaccharic,  265. 
margaric,  255. 
meconic,  397. 
mesotartaric,  264,  265. 
mesoxalic,  266. 
metaboric,  124. 
metanitrous,   101. 
metantimonic,  122. 
metantimonous,    122. 
metaphosphoric,  109. 
metarsenic,  114. 
metarsenous,   113. 
metastannic,   146. 
metatungstic,   128. 
methan,  251. 
methylacetic,  253. 
methylethylamido     propionic, 

325. 

metliylguanidinacotie,  302. 
monochloracetic,   253. 
morintannic,  300. 
morphinesulphuric,   434. 
morphylsulphuric,  434. 
morrhiiio,  442. 
mucic,  265. 
muriatic,  76. 
myristic,  255. 
myronic,   363. 
nitric,  101. 
nitroacetic,  321. 
nitrohydrochloric,  102. 
nitrosonitric,  102. 
nitrosulphonic,  99. 
nitrous,  101. 
octylic,  255. 
oleic,  331. 
opianic,  436. 
orthoamidobenzoic,  374. 
orthoantimonic,    122. 
orthoarsenic,   113. 
orthoboric,   124. 
orthorarbonic,  109. 
orthoformio.  252. 
ortbopbcnylaulpbonic,   366. 
orthophosphoric,  108. 
osmic,  12S. 
oxalic,  257. 
oxaluric,  318. 
oxanilic,  374,  375. 


INDEX 


453 


Acid,  oxyacetie,  202. 

oxybfctyric,  263. 

oxyformic,  261. 

oxyglutaric,   263. 

oxyhydratropic,   364. 

oxymalonic,  263. 

oxyphenic,  349. 

oxypropionic,   262,  263. 

oxysuccinic,  263. 

palmitic,  255. 

paraamidobenzenesul phonic,  371. 

parabanic,  395. 

paralactic,  262. 

paratartaric,   264. 

pentathionic,    89. 

perchloric,  79. 

periodic,  83. 

persulphuric,   92. 

phenic,  345. 

phenylacetic,  356. 

phenylamidopropionic,    374. 

phenylmalonic,   356. 

phenylsulphuric,  366. 

phloretic,  364. 

phosphatic,    109. 

phosphomolybdic,   128. 

phosphoric,   108. 

phosphorous,   108. 

phosphotungstic,   128. 

phthalamic,  373. 

phthalic,  357. 

picric,  369. 

propan,  253. 

propionic,  255. 

propylacetic,  254. 

prussic,   303. 

purpuric,  404. 

pyridinedicarboxylic,  430. 

pyridinetartronic,   428. 

pyroantimonic,   122. 

pyroarsenous,   113. 

pyroboric,  124. 

pyrocateehnic,  359. 

pyrogallic,  350. 

pyromucic,  392. 

pyrophosphoric,   109. 

pyroracemic,  266. 

pyrosulphuric,  93. 

pyrotartaric,  259,  264. 

pyruvic,  264,  266. 

quercitarmic,  360. 

quinic,  384,  429. 

quinotannic,  360,  429. 

quinovic,  429. 

racemic,  264,  265. 
Acid  reaction,  32. 
Acid,  rosolic,  350. 

saccharic,  265. 

salicylic,  358. 

salicylous,  354. 

sarcolactic,  262. 

sebasic,  332. 

silicotungstic,  128. 


Acid,  sozolic,  366. 
stannic,    146. 
stearic,  255. 
strychnic,  432. 
succinic,  259. 
sulphanilic,  371. 
sulphydric,  85. 
sulphocarbamic,   316. 
sulphocyanic,  308. 
sulphovinic,  268,  277. 
sulphuric,  90. 
sulphurous,  89. 
tannic,  360. 
tartaric,  239,  264,  265. 
tartronic,  263. 
terebic,  384. 
terephthalic,  357. 
terpenylic,  384. 
tetraboric,  124. 
tetrathionic,  89. 
thioacetic,  287. 
thiobenzoic,  365. 
thiocarbamic,  316. 
thiocyanic,  308. 
thiosulphtiric,  92. 
trichloracetic,  253. 
trichromic,  131. 
tricyanic,  307. 
trihydrocyanic,  310. 
trinitrophenic,  369. 
trithionic,  89. 
uric,  406. 
uroleucic,  359. 
urous,  410. 
valerianic,  254. 
valeric,  254. 
vanillic,  354. 
xanthic,  410. 

Acids,  36,  39   (see  Acid), 
acetic  series,  250. 
alcohol,  259. 
aldehyde,  265. 
alkyl  benzoic,  356. 
amic,  310,  313. 
amido,  321. 

butyric,  325. 

caproic,  325. 

cinnamic,  374. 

phenyl,  373,  374. 

propionic,  325. 

valeric,  325. 
anil,  376. 
anilic,  375. 
anilido,  374,  375. 
aromatic  amido,   373. 

carboxylic,  355. 

dioxycarboxylic,  358. 

monocarboxylic,,  355. 

polycarboxylic,  356. 

trioxycarboxylic,  359. 
atomicity  of,  259. 
basicity  of,  36,  259. 


454 


INDEX 


Acids,  ben/me  dicarboxylic,  357. 

disulphonic,  .'»»»(>. 
benzole  series,  355. 
camphoric,  384. 
caproic,  254. 
carbopyridic,  .'5!) 7. 
carboxylic,  250. 
cresylic,  347. 
dibasic,  30. 
dicarboxylic,  265. 
dioxydicarboxylic,  264. 
dioxyethylene  succinic,  264. 
dioxymonocarboxylic,  358. 
dioxyphenyl,  359. 
dioxytoluic,  359. 
fatty,  250. 
hexan,  254. 
hexylic,  254. 

hydroaromatic,  383,  384. 
hydrophthalic,   357. 
hydroxamic,  300,  301,  376. 
indolecarboxylic,  415. 
ketonic,  266. 
lactic,  262. 
mannosaccharic,  265. 
mineral,  77. 
monamido,  321. 
monobasic,  36. 

monocarboxylic  aromatic,  3f>.~>. 
monoketone  monocarboxylic,  266. 
monoxydicarboxylic,  20.'!. 
monoxymonocarboxylic,  357. 
naphthol  sulphonic,  387. 
nitro,  321,  370. 
nitrobenzenic,  370. 
nitrobon/oic,   370. 
of  antimony,   122. 

arsenic,  113. 

nitrogen,    100. 

phosphorus,  107. 

sulphur,  89. 
olefinedicarboxylic,  332. 
oleic,  331. 
ortho,  108. 
oxalic   series,  256. 
oxyacetic,  260. 
oxyaldehyde,  266. 
oxybenzoic,  357. 
oxybutyric,  263. 
oxyketone,  266. 
oxypropionic,  262. 
oxytricarlioxylic.   265. 
paraffin  dirarboxylio,  256. 

monocarboxylic,  250. 
pentan,   254. 
phenol    carlioxylic.    357. 

phenyl  amido,  :).73,  374. 
bitty,  .",.-><•.. 
propionic,   35(i. 

plithaiic.  :::.«;. 

polyliasic.    .",0. 

pyrrolidmcarboxylic,  393. 

radical   of,   -10. 


Acids,  residue  of,  46. 

saccharic,  265. 

sulphinic,  277,  286,  366. 

sulplionic,  277,  284,  286,  365. 

sulphurous,  89. 

tannic,  360. 

tartaric,  2:5!),  264. 

tetro.xydicarbo.x  yl  ic,   205. 

thiocarbamic,  310. 

thiosulphonic,   2SO. 

tolueni'sul phonic,  :>00. 

tribasic,  :>0. 

trioxymonocarboiylic,  359. 

valerianic,  254. 

valeric,  254. 

volatile  fatty,  250. 
Acidulous  elements,  52,  73. 
Ac-idyl  halidcs,  270. 

hydroxides,  250. 
Acidylenes,  256. 
Aconine,  440. 
Aconite  alkaloids,  440. 
Aconitine,  440. 
Acroleine,  330. 
Acrose,   240. 

Acyclic  compounds,  199,  201. 
Acylation,  284. 
Addition,  197. 
Adenine,  412. 
Adipocere,  444. 
Adjacent  positions,  338. 
Adonite,  225. 
JCsculetin,  362. 
JEsculin,  362. 
Affinity,  48. 
After-damp,  204. 
Air,  See  Atmospheric  air. 
Alabaster,  109. 
Alanine,  375. 
Alanines,  322,  325,  375. 
Albite,   180. 
Alcohol,  214,  217    (see  Alcohols). 

absolute.  215,  217. 

acids,  259. 

allyl,  330. 

am'idoethyl,  319. 

amylic,  220. 

benzyl ic,  352. 

butylic,  220. 

debydratum,  217. 

denatured,  218. 

dilutum,  217. 

cslcvs.   275. 

ctliylcnc,  222. 

ethylic,  214. 

isobutylic,  220. 

methylic,  214. 

nitrocl hylic.   319. 

oxylicii/ylic,    352. 

propenyl,  223. 

t  ropan.  1'2.'>. 

vinyl,  214. 

wood.  214. 


INDEX 


455 


Alcoholates,  213. 
Alcohol!^  beverages,  218. 

fermentation  215,  218. 
Alcohols,  210. 

amido,  319. 

amylic,  220. 

aromatic,  351. 

butyl,  220. 

camphan,  383. 

cinnamic,  352. 

diatomic,  221,  352. 

dihydric,  221,  352. 

diphenyl,  380. 

heptatomic,  225. 

hexatomic,  225. 

hexahydric,  225. 

hydroaromatic,  382. 

iso,  211. 

menthan,  383. 

monoatomic,   211. 

monohydric,  211. 

nomenclature  of,  211,  221. 

nonatomic,  225. 

octatomic,   225. 

oxyplienyl,  352. 

pentatomic,  225. 

pentahydric,  225. 

polyatomic,   224. 

polyhydric,  224. 

primary,  211,  212,  213. 

propyl,'  219. 

ring,  382. 

secondary,  211,  212,  214,  352. 

tertiary,' 211,  212,  214,  352. 

tetratomic,  225. 

tetrahydric,  225. 

triatomic,  223,  352. 

trihydric,  223,  352. 
Aldehyde,  acetic,  229. 

acids,  2G5. 

acrylic,  330. 

ammonia,  227,  230,  296,  319. 

anisic,  354. 

benzoic,  353. 

formic,  228. 

glyceric,  237. 

glycolyl,  237. 

hydrazones,  321. 

methylprotocatechuic,  354. 

salicylic,  354. 
Aldehydes,  225,  226. 

aromatic.  353. 

define,  330. 
Aldehydrazones,    380. 
Aldoses,  236. 
Aldoximes,  320. 
Ale,   218. 

Algaroth,  powder  of,  121. 
Aliphatic  compounds,  199,  201. 

unsaturated,  327. 
Alizarin,   388. 
Alkali,  149. 

carbonated,   149. 


Alkali,  caustic,  149. 

metals,  149. 

volatile,  95,   149. 
Alkaline  earths,  metals  of,  168. 

reaction,   33. 
Alkaloids,  419. 

aconite,  440. 

cinchona,  428. 

classification  of,  421. 

general  reactions  of,  421. 

isoquinoline,  421,  433. 

loganiacese,  431, 

nomenclature  of,  420. 

opium,  434,  437. 

phenanthrene,  422,  433. 

piperideine,  421. 

piperidine,  421,  422. 

properties  of,  420. 

pyridine,   421. 

pyrrolidine,  421. 

piperidine,  421,  424. 
pyridine,  421,  423. 

quinoline,  421,  429. 

strychnos,  431. 

tropan,  421,  424. 
Alkanes,   202. 
Alkaptonuria,  359. 
Alkarsin,  326. 
Alkyl,  202. 

'halides,   205. 

hydroxides,  211. 

pyridines,  398. 

pyridinum  iodides,  397. 

ureas,  316. 
Alkylation,   284. 
Alkylenes,  221. 
Allantoin,  395. 
Allene,  330. 

Allometa  position,  339. 
Allortho  position,  339. 
Allotropy,  9. 
Alloxan,  405. 
Alloxantin,  404. 
Alloxuric  bases,  409. 
Alloys,  185. 
Allyl  alcohol,  330. 

amine,  333. 

isothiocyanate,  333. 

oxide,  333. 

sulphide,  333. 
Allylene,  330. 
Alphenols,  352. 
Alumina,  178. 
Aluminates,  178. 
Aluminium,   178. 

bronze,  178. 

chloride,  179. 

group,  177. 

hydroxide,    178. 

oxide,   178. 

silicates,   180. 

sulphates,  179. 
Alums,   179. 


456 


INDEX 


Amalgams,  185. 
Amanitine,  21)0. 
Amide  nitrogen,  293. 
Amidines,  300. 
Amido  acetaldehyde,  319. 
acetones,  319. 
acids,  321. 

aromatic,   367. 
alcohols,  319. 
aldehydes,  311). 
azo  compounds,  379. 
benzenes,  371. 
benzol,  371. 
group,  293. 

ketodihydropyrimidine,  403. 
ketones,  319. 
ketopurine,  411. 
paraffins,  292. 
phenyl   acids,   367. 
phenylalanine,  375. 
phenols,  373. 
purine,  412. 
xylenes,  372. 
Amidoximes,  300,  376. 
Amides,     310     (see    Monamides,    Dia- 

mides). 

aromatic,  367,  373. 
mixed,  310. 

of  dicarboxylic  acids,  313. 
Amine  bases,  292. 
nitrogen,  293. 
Amines,    292     (see    Monamines,    Dia- 

mines.) 

aromatic,  367. 
Ami  no  group,  293. 
Ammelide,  315. 
Ammonia,  95. 

aldehyde,  227,  230,  296,  319. 
bismuth  of,  167. 
caustic,  166. 

Ammonias,  compound,   293. 
Ammonio-magnosium  phosphate,  174. 
Ammonium,  96,  165. 
acetate,  167. 
alum,   179. 
amalgam,  166. 
bromide,  167. 
carbonates,   167. 
chloride,  96,  166. 
compounds,  165. 
cyanate,  307. 
derivatives.  292. 
hydroxide,  96,  106. 
iodide,  167. 
nitrate,  167. 
sesquicarbonate,  167. 
sulphates,  167. 
sulplmlrate,   166. 
sulphides,  166. 
theory,  105. 

Amorphous   substances,  4. 
Ampere,  21. 
Amphoteric  elements.  53,  129. 


Amphoteric  reaction,  33. 
Amygdalin,  303,  362. 
Amyl  nitrate,  279. 

nitrite,  279. 
Amylene,   330. 

hydrate,   221. 
Amylum,  245. 
Analysis,  33,  63. 
organic,   194. 

Analytical  characters  of  alcohol,  218. 
aluminium,  180. 
ammonia,  96. 
ammonium,    167. 
aniline,  371. 
antimony,  123. 
arseni?,  116. 
atropine,  426. 
barium,  172. 
bismuth,   144. 
bromidion,  81. 
brucine,  433. 
cadmium,  177. 
calcium,  171. 
carbolic  acid,  346. 
carbon   dioxide,   274. 
chloridion,  78. 
chloroform,  206. 
chromium,  131. 
cobalt,  181. 
cocaine,  428. 
conime,  422. 
copper,  183. 
cyanides,  304. 
fluorine,  74. 
formaldehyde,  229. 
glycerol,  224. 
gold,  130. 
hydrogen,  59. 
dioxide,  70. 
sulphide,  87. 

iodidion,  83. 
iron,  137. 

lead,  141. 

lithium,  150. 

magnesium,  175. 

manganese,   132. 

mercury,  189. 

morphine,  435. 

nickel,  181. 

nicotine,  424. 

nitrates,  102. 

nitrobenzene,  368. 

oxalates,  258. 

oxygen,  61. 

ozone,  62 

phenol,  346. 

phosphates.   109. 

phosphorus,   106. 

potassium,   163. 

quinine,   429. 

silver,    105. 

sodium,    156. 

strontium,  171. 


INDEX 


457 


Analytical  characters  of  strychnine,  432. 

sulphates,  92. 

sulphides,  87. 

sulphites,  89. 

sulphur  dioxide,  88. 

tin,  146. 

zinc,  177. 
Anethol,  354. 
Anglesite,  138. 
Anhydride,  acetic,  269. 

antimonic,   122. 

antimonous,  121. 

arsenic,  113. 

arsenous,  112. 

benzoic,  364. 

boric,  124. 

carbonic,   272. 

chromic,  130. 

hypochlorous,   79. 

molybdic,   128. 

nitric,   100. 

nitrous,  99. 

phosphoric,  107. 

phosphorous,  107. 

phthalic,  364. 

plumbic,  139. 

salicylic,  364. 

silicic,  127. 

succinic,  259. 

sulphuric,  88. 

sulphurous,  87. 

titanic,   145. 

tungstic,  128. 
Anhydrides,  46,  61. 

'acid,  269. 

aromatic,  364. 

halide,  270. 

thio,  87. 

Anhydroecgonine,  427. 
Anilido  acids,  374,  375. 
Anilides,  372. 
Aniline,   371. 

dyes,  373,  376. 
Anions,  20,  35,  45. 
Anisidines,  369,  372. 
Anisol,   360. 
Annidalin,  348. 
Anode,   19. 
Anthracene,   386. 

oil,  341. 

Anthracite,  125. 
Antifebrine,  372. 
Antimony,  120. 

acids  of,  122. 

black,  122. 

butter  of,  121. 

chlorides  of,  121. 

crocus  of,  122. 

crude,  122. 

glass  of,   122. 

liver  of,  122. 

organic  compounds  of,  326. 

oxides  of,  121. 


Antimony,  pentachloride,  121. 

pentasulphide,  122. 

pentoxide,   122. 

sulphides  of,  122. 

tartrated,  162. 

trichloride,    121. 

trioxide,  121. 

trisulphide,   122. 

Antimony  1  potassium  tartrate,  162. 
Antipyrine,  394. 

salicylate,  394. 
Antiseptics,    444. 
Apoatropine,  427. 
Apomorphine,  434,  436. 
Apoquinine,   430. 
Aqua  ammoniae,  96. 

destillata,  67. 

fortis,   101. 

regia,  77,  102. 

sapphirina,   183. 
Arabin,  246. 
Arabinose,  237. 
ArecaTne,  422. 
Argol,  161. 
Argon,  72. 
Aricine,  429. 
Aristol,   348. 

Aromatic  compounds,  200,  334,  336. 
Arragonite,   170. 
Arsenates,  115. 
Arsenic,  110,  112,  115. 

antidote,  115. 

bisulphide,  114. 

halides,  112. 

organic  compounds  of,  326. 

pentasulphide,  114. 

pentoxide,  113. 

trichloride,   112. 

triiodide,   112. 

trioxide,  112,  115. 

trisulphide,  114. 
Arsenical  greens,  115. 
Arsenites,  113. 
Arsine,  111. 

dimethyl,  326. 
Arsines,  326. 
Artesian  wells,  65. 
Artiads,  30. 
Asbestos,  173. 
Aselline,  282. 
Aseptol,  366. 

Asymmetric  carbon  atom,  329. 
Atmospheres,  4. 
Atmospheric  air,  72,  94. 

ammoniacal  compounds  in,  95. 

analysis  of,  274. 

carbon  dioxide  in,  95,  272,  274. 

nitrous  acid  in,  95. 

rare  elements  in,  72. 

solid  particles  in,  95. 

sulphurous  acid  in,  95. 

water  in,  95. 
Atom,  25,  26. 


458 


INDEX 


Atomic  rearrangement,  33. 

theory,  24. 

weight,  26. 
Atomicity,  30,  37. 
Atropamine,  427. 
Atropine,    \-~>. 
Auric  chloride,  129. 
Aurin,  350. 
Auroamidoimide,  308. 
Aurous  chloride,   129. 
Avogadro,  postulate  of,  24. 
Azines,  398. 
Azobenzene,  378,  379. 
Azo  compounds,  367,  376,  378. 

dyes,  376. 
Azoimide,  97. 
Azoles,  393. 

Azonaphthol   compounds,  387. 
Azo  nitrogen,  293. 
Azote,  94. 
Azoxy  benzene,  378. 
Azoxy  compounds,   378. 

Baking  powders,  161. 
Balsams,  385. 
Barium,  171. 

carbonate,  172. 

chloride,  172. 

dioxide,   172. 

hydroxide,  172. 

monoxide,    171. 

nitrate,  172. 

oxides,  171. 

sulphate,  172. 
Baryta  water,  171,  172. 
Bases,  36,  39. 

acidity  of,  37. 

atomicity  of,  37. 
Bassorin,  246. 
Basylous  elements,  53,  149. 
Battery,  galvanic,  19. 
Bauxite,  178. 
Beer,  218. 
Belladonnine,  427. 
Benzamide,  356,  373. 
Benzeno,  334,  341. 

amido,  371. 

amido  derivatives  of,  367,  371. 

azomethane,   378. 

azoxy,  378. 

halides,  343. 

homologues  of,  341. 

hydroxylamine  derivatives  of,  367, 
370. 

imido  derivatives  of,  367. 

nitro,  367. 

nitro  derivatives  of,  367. 

nitrogen  derivat  ives  of,  367. 

nitroso  derivat  i\  TS  of,  367. 

nucleus,  334. 

oxygen  compounds  of,  343. 


sulphoehloride,    366. 


Benzenyl,  356. 

amidine,  356. 

amidoxime,  376. 
Benzhydrol,   :$S9. 
Benzidine,  371). 
Benzine,  20}. 
Benzol,  341. 
Benzolene,  204. 
Benzonitrile,  373. 
Benzophenol,  345. 
Benzopyridine,    414. 

bases,  418. 
Benzopyrrole,  415. 
Benzoquinone,  351. 
Benzosol,  349. 
Benzosulphinide,  366. 
Benzoyl,  343. 

amide,  373. 

chloride,  364. 

ecgonine,  427. 

glycocoll,  375. 

hydride,  353. 

morphine,  434. 

sulphonic  imide,  366. 
Benzyl,  343. 

benzene,  388. 

chloride,  343. 

hydrate,  352. 
Betaine,  298. 

trimethylacetic,  298. 
Betames,  207. 
Beverages,  alcoholic,  218. 
Bieberich  scarlet,  387. 
Bilineurin,  296. 
Bismark  brown,   101. 
Bismuth,  142. 

hydroxide,   143. 

magma  of,  143. 

milk  of,  143. 

nitrate,   143. 

of  ammonia,  167. 

oxides  of,  143. 

subcarbonate,  143. 

subnitrate,  143. 

trichloride,  143. 

trinitrate,   143. 

trioxide,  143. 
Bismuthates,  142. 
Bismuthyl,  142. 

carbonate,  143. 

chloride,    143. 

hydroxide,  143. 

nitrate,  143. 
Biuret,  315,  317. 
Black  wash,    lSf>. 
Illraehing  powder,   169. 
Blende,    17.">. 
Ulue   stone,   183. 
Boiling,  lf>.  Hi. 

point.   12,  16. 

absolute,    16. 
Bone  ash,   170. 

Maek,    1-JU. 


INDEX 


459 


Bone  oil,  397. 

phosphate,  170. 
Borax,  154,  214. 
Bordeaux  dyes,  387. 
Borneo  camphor,  383. 
Borneol,  383. 
Boroglyceride,   124. 
Boron,  123. 

trioxide,    124. 
Braunite,   131. 
Brimstone,   84. 
British  gum,  246. 
Bromamide,  312. 
Bromidion,  81. 
Bromides,  80. 
Bromine,  80. 
Bromoform,    207. 
Bromophenols,  348. 
Brucine,  433. 
Butalanine,  325. 
Butyl  morphine,  434. 
Butyrolactam,  393. 

Cacodyl,  326. 

cyanide,  327. 

oxide,  326. 
Cadaverine,  299. 
Cadet,  liquid  of,  326. 
Cadmium,  177. 
Caesium,  163. 
Caffeine,  411. 
Calamine,   176. 
Calcium,  168. 

acetylide,  329. 

carbide,    169. 

carbonate,    170. 

chloride,  169. 

group,   168. 

hydrate,   169. 

hydroxide,   169. 

hypochlorite,  169. 

oxalate,   170. 

oxide,  168. 

phosphates,  170. 

plumbite,  139. 

sulphate,  169. 
Calcspar,  170. 
Calomel,  186. 
Calorie,  12. 

Camphan  alcohols,  383. 
Camphol,  383. 
Camphor,  384. 

Borneo,  383. 

Japan,  384. 

laurel,  384. 

monobromo,  384. 
Camphors,  384. 
Camphoryl  morphine,  434. 
Campobello,  yellow,  387. 
Cane  sugar,  242. 
Caramel,  243. 
Carbamide,  314. 
Carbamines,  306. 


Carbides,  329. 
Carbimide,  318. 
Carbinol,  211,  214. 

butyl,  220. 

diethyl,  221. 

diphenyl,  389. 

diphenyltoluyl,   389. 

ethyl,  219. 

ethyldimethyl,  221. 

ethylmethyl^  220. 

isobutyl,  220. 

isopropyl,  220. 

methyl,   214. 

methylisopropyl,  221. 

methylpropyl,   221. 

phenyldimethyl,   352. 

phenylmethyl,  352. 

propyl,   220. 

trimethyl,  220. 

triphenyl,  389. 

Carbocyclic  compounds,  200,  334,  335. 
Carbodiimides,  372. 
Carbohydrates,  235. 

tests  for,  247. 
Carbolates,  346. 
Carbolic  oil,  341. 
Carbo  animalis,  126. 

ligni,  125. 
Carbon,  124. 

amorphous,  125. 

compounds  of,  191. 

dichloride,  207. 

dioxide,  272. 

disulphide,  287. 

group  124. 

metallic,  125. 

monoxide,  270. 

hemoglobin,  271,  273. 

oxides  of,  270. 

oxysulphide,  288. 

tetrabromide,  207. 

tetrachloride,  207. 

trichloride,  207,  280. 

valence  of,   196. 
Carbonic  acid  gas,  272. 
Carbonic  anhydride,  272. 

oxide,  270. 

Carbonous  oxide,  270. 
Carbonyl,   198. 

chloride,  271. 

diurea,  318. 
Carborundum,  127. 
Carbotriamine,  301. 
Carboxime,  320. 
Carboxyl,  198. 
Carbylamines,  295,  306. 
Carbyloxime,  307. 
Carn'allite,    157. 
Carnine,  409,  413. 
Carvacrol,  348. 
Carvol,  348. 
Cassel  yellow,  140. 
Cassiterite,   145,  146. 


460 


INDEX 


Cassius'  purple,  129. 
( 'atalysers,   .IS. 
Cathode,  19. 
Cations,  20,  35,  45. 
Celestine,   171. 
Cellulin,  247. 
CVlluloid,  247. 
Cellulose,  247. 

nitro,  247. 
Celsius'  scale,  12. 
Centigrade   scale,    12. 
Cerebrin,  241. 
Cerebrose,  241. 
Ceruse,    141. 
Cerusite,  141. 
Cetaceum,  279. 
Cetin,  279. 
Cetyl  palmitate,  279. 
Chains,  199,  200. 
Chalk,  170. 

precipitated,  170. 

prepared,  170. 
Characterizing  groups,  198. 
Charcoal,  125. 

animal,   126. 

wood,  125. 
Chelidonine,  397. 
Chemical  affinity,  48. 

change,  1. 

displacement,  48. 

energy,  48. 

equilibrium,  49. 

equivalent,  31. 

force,  48. 

stability,  48. 

system,  49. 
Chemism,  48. 
Chemistry,  1. 

general,  1. 

inorganic,  57. 

organic,  191,  192. 
Chinovose,  237. 
Chloral,  230,  231. 

alcholate,  232. 

hydrate,  231. 
Chloralamide,  312. 
Chloraldide,  232. 
Chloralide,  232. 
Chloralimide,  312. 
Chloralum,  170. 
Chloride  of  lime,  169. 
Chloridion,  78. 
Chlorides,  78. 
Chlorinated  lime,  169. 
Chlorine,  74. 

group,  73. 

monoxide,  79. 

peroxide,  79. 

tetroxide,  79. 

water.  7"). 

Chloroben/.cnes,  343. 
Chloroform.   2<MJ. 
Clilornphenols,    348, 


Chlorophyll,  228,  274. 
Chloroplatinates,   148. 
Chlorozone,  155. 
Cholinc,  290. 
Chromates,  131. 
Chrome  yellow,   140. 
Chromium,    130. 

oxides  of,  130. 

sulphates  of,  131. 
Cider,  219. 
Cinchona  alkaloids,  428,  430. 

red,  429. 

Cinchonicine,  430. 
Cinchonidine,  430. 
Cinchonine,  429,  430. 
Cineol,  383. 
Cinnabar,    184. 
Circuit,  electric,  19. 
Cisterpin,  383. 
Classification  of  alkaloids,  421. 

of  aromatic  compounds,  339. 

of  carbocyclic  compounds,  335,  339. 

of  carbohydrates,  236. 

of  elements,   51. 

of  heterocyclic  compounds,  390. 

of  organic  compounds,  199. 
Clay,  180. 

Closed  chain  compounds,  200,  334. 
Coal,  125. 

tar,  341. 
Cobalt,  181. 
Cocaine,  427. 
Codeine,  436,  438. 
Cohesion,  4. 
Coke,  126. 
Colchicine,  441. 
Collidines,  398. 
Colloids,  9. 
Colophony,  382. 
Columbium,   128. 
Combinations,  33. 
Combustion,  60. 

supporters  of,  60. 
Composition,  46,  196. 
Compound  ammonias,  293. 
Compounds,  22. 
Compounds,  acyclic,  201. 

aliphatic,  *201. 

aromatic,  200,  334,  336. 

carbocyclic,  200,  334,  335. 

closed  chain,  200,  334. 

cyclic,  200,   334. 

fatty,  201. 

hotorocyclic,  334,  389,  414. 

hoxacarbocyclic,   336. 

monobenzenic,  341. 

open  chain,  201. 

organic,   192,  201. 

saturated,    196,  201. 

unsaturated,   107. 
Concentration,   !).   37. 
Condensation.    11,    1  (i.    li'J'.). 
Cond<  used    carbocyclie   compounds.    .'^.~> 


INDEX 


461 


Condensed  heterocyclic  compounds,  414. 

nuclei,  385. 

Condensing  agents,  229. 
Conductors,  17. 
Condy's  fluid,  155. 
Congelation,  15. 
Conhydrine,   422. 
Coniferin,  354,  362. 
Coniceme,  422. 
Coniiine,  398,  422. 
Consecutive  positions,  338. 
Constitution,  46,  193,  196. 
Contact  agent,  268. 
Copper,   181. 

acetates,    183. 
acetylide,  329. 
ammonio-sulphate,  183. 
chlorides,  182. 
group,  181. 
hydroxides,  182. 
oxides,  182. 
reduction  tests,  248. 
Copperas,    135. 
Coprolites,  170. 
Corallin,  350. 
Cordials,  219. 
Corrosive  sublimate,  187. 
Corrosives,  78,  and  see  Toxicology. 
Corundum,  178. 
Cosmoline,  204. 
Cotarnine,  436,  438. 
Coulomb,  21. 
Cream  of  tartar,  161. 
Creasol,  347. 
Creosote,  347. 

oil,  341. 
Creatine,  302. 
Creatinine,  302. 
Creolin,  347. 
Cresols,  347. 
Cresylols,  347. 
Crith,  58. 
Cryolyte,  73,  178. 
Crystallization,  4. 

water  of,  8,  63,  64. 
Crystalloids,  9. 
Crystals,  5. 
Cupric  acetate,  183. 
arsenite,  183. 
chloride,  182. 
hydroxide,   182. 
nitrate,  182. 
oxide,  182. 
sulphate,  183. 
Cuprous  chloride,  182. 
hydroxide,  182. 
oxide,  182. 
Curarine,  433. 
Cyamelide,  307. 
Cyanamide,  309. 
Cyanidine,  414. 
Cyanides,  303,  305. 
Cyanobenzene,  373. 


Cyanogen,  303. 

chlorides,  304. 

compounds,   303. 

hydride,  303. 

sulphydrate,   308. 
Cyclic  compounds,  200,  334. 
Cyclodiolefine,  335. 
Cyclohexane,  335. 
Cycloparamns,  335. 
Cyclotriolefine,  335. 
Cymene,  342. 
Cymogene,  204. 
Cytosine,  403. 

Daphnetin,   362. 
Daphnin,  362. 
Deamidation,  323. 
Decompositions,  33. 

double,  33,  37. 

primary,  34. 
Defuselation,  220. 
Dehydromorphine,  434. 
Deliquescence,  15,  16. 
Density  absolute,  3. 

relative,  3. 
Deodorizers,  444. 
Deoxidation,   58. 
Deoxystrychnine,  432. 
Derived  substances,  208. 
Dextrin,  246. 
Dextrose,  240. 
Diabetic  sugar,  240. 
Diacetine,  223. 
Diacetonamine,  319. 
Diacetylene  series,  201. 
Diacetylethylenediamine,   298. 
Diacetylmorphine,  434. 
Diachylon,  139. 
Dialdehydes,  233. 
Dialysis,  9. 
Diamide,  96. 
Diamides,  310. 

primary,  314. 
Diamidodiphenol,  379. 
Diamine  diacetylethylene,  299. 

diethylene,  400. 

ethylene,  299. 

pentamethylene,  299. 

phenylene,  380. 

tetramethylene,  299. 

trimethylene,  299. 
Diamines,   292,  296,  298. 
Diamond,  125. 
Diastase,  214. 
Diazines,  399. 
Diazo, 

amido  compounds,  367. 

benzene  chloride,  376. 

compounds,  376. 

dyes,  379. 

nitrogen,  293. 
Diazoles,  393,  394. 
Diazotizing,  377. 


462 


INDEX 


Dibromomethyl  bromide,  207. 
Dicacodyl,  326. 
Dichlormethane,  206. 
Dichlorincthyl    chloride,  206. 
Dievanogen,  .'!07. 
Diethylcarbinol,  221. 
Diethylenediamine,    400. 
Diethylmalonylurea,   404. 
Diethyl  sulphite,,  277. 
Diffusion  of  liquids,  9. 
Diglycerides,  223,  280. 
Digital iresin,  363. 
Digitalis  glucosides,  363. 
Digitalin,  363. 
Digitalose,   363. 
Digitogenin,  363. 
DigitoneTn,  363. 
Digitonin,  363. 
Digitoxin,  363. 
Dihydrobenzenes,  335. 
Dihydrofurfurane,  392. 
Dihydropyridines,  398. 
Dihydropyrrole,  393. 
Dihydrostrychnoline,  432. 
Diimines,  296. 
Diindoxyl,  418. 
Diiodomethyl  iodide,  207. 
Diketones,  233,  235,  354. 
Diketopurine,  410. 
Diketotetrahydroglyoxalin,   395. 
Diketotetrahydropyr  imidine,  401 . 
Dimethyl  aniine,  295. 

arsine,  326. 

benzenes,  342. 

iodoles,  415. 

ketone,  234. 

malonylurea,  404. 

pyrazolon,  395. 

pyridines,  398. 
Dimorphism,  8. 
Dinitrobenzenes,  368. 
Dinitronaphthols,  387. 
Dinitrophenols,  369. 
Dinitrosoresorcinol,  370. 
Diolefines,  201,  330. 
Diols,  221. 
Dionine,  434. 
Dioses,  236,  237. 
Dioxindole,  374. 
Dioxyacetone,  237. 
Dioxyanthraquinone,  388. 
Dioxymet  liylanthraquinone,  388. 
Dioxypurine,  410. 
Diphenyl,  388. 

acetylene,   388. 

benzene,  388. 

Diplienyleiic    (1  iket  one  ,    .387. 

Diphenyl  ethylene,  IIS!). 
hydra/ine,   :J7'.>. 

methane, 
oleftnee, 

oxide,    .".tilt, 
parall'ms. 


Disaccharides,  236,  241. 

Disacryl,  331. 

Disdia/oamido  compounds,  377,  3*78. 

Disinfectants,  444. 

Displacement,  48. 

Dissociation,  35,  64. 

Distillation,  16,  67. 

fractional,  16. 
Diureides,  317. 
Divisibility,  2. 
Dolomite,  174. 
Dulcin,  225. 
Dulcitan,  225. 
Dulcite,   225. 
Dulcitol,  225. 
Dulcose,  225. 
Dutch  liquid,  280,  328. 
Dyads,  30,  31. 

Ebullition,  15. 
Ecboline,  441. 
Ecgonine,  398,  427. 
Efflorescence,  9. 
Elayl,  327. 

chloride,  280. 
Electric  circuit,   19. 

conductance,  20. 

conductivity,  20. 

current,    19. 

resistance,  20. 

units,  21. 
Electricity,   17. 

galvanic,  18. 

negative,  17. 

positive,   17. 

resinous,  17. 

vitreous,  17. 
Electrodes,  10. 

Electrochemical  series,  33,  34. 
Electrolysis,  20,  33. 
Electrolyte,  20. 
Electromotive  force,  20. 
Electronegative,  33,  34. 
Electropositive,   33,   34. 
Elements,  21,  27. 

acidulous,  52,  73. 

amphoteric,  53,  129. 

basylous,  53,  149. 

classification  of,  51. 

electronegative.  :;::.  ::i.  52. 

electropositive.  :;:;.  :\\,  53. 

equivalence  of,  30. 

in  earth's  crust,  21. 

in  human  body,  21,  22. 

typical,    52,    57. 

which  form  no  compounds,  .VJ,  7'2. 
Elutriat  ion,    170. 
Emerald,  178. 
Kmery,    ITS. 
Minet  ine,    4-1  1 . 
Kinulsifying   agents,   282. 
Emulgin,  ::»;i. 
Knuilsion,  282. 


INDEX 


463 


Energy,  3. 

chemical,  48. 

kinetic,  3. 

potential,   3. 
Enzymes,  216. 
Eosin,  350. 
Epiguanine,   413. 
Episarkine,  409,  413. 
Epsom  salt,  173. 
Equations,  32. 
Equilibrium,  apparent,  50. 

chemical,   49. 

dynamic,  49. 

heterogeneous,  49, 

homogeneous,  49. 

real,  49. 
Equivalence,  30. 
Equivalent,  37. 

chemical,  31. 

osmotic,  9. 
Ergotine,  441. 
Erythrin,  224. 
Erythrite,  224. 
Erythrodextrin,  246. 
Erythrol,  224. 
Erythrose,  237. 
Eserine,  441. 
Essence  of  Mirbane,  367. 

of  turpentine,  382. 
Essences,  282. 
Ester,  acetoacetic,  278. 

malonic,  279. 

methylenemalonic,  332. 

sulphates,  367. 
Esters,  267,  275. 

alcohol,  275. 

dioxymalonic,  266. 

haloid,  205,  279. 

hyposulphurous,  277. 

isothiocyanic,  80S. 

of  carbamic  acid,  313. 

of  dihydric  alcohols,  279. 

of  glycerol,  280. 

of  glycols,  279. 

of  monohydric  alcohols,  276. 

of  oxyacids,  283. 

of  trihydric  alcohols,  280. 

orthoformic,  277. 

oxymalonic,  266. 

thiophosphoric,    285. 

sulphurous,  277. 
Ethanal,  229. 
Ethene,  327. 

chlorhydrine,  222. 

compounds,  328. 

glycol,   222. 

homologues  of,  328. 

series,  327. 

Ethenylamidoxime,  300. 
Ether,  acetic,  278. 

allylic,  333. 

dimethylpyrocatechuic,  349. 

ethyl ic,  268. 


Ether,  ethylphenyl,  361. 

hydriodic,  208. 

hydrobromic,  208. 

hydrochloric,  208. 

methylphenyl,  360. 

monomethylpyrocatechuic,   349. 

muriatic,  208. 

nitric,  276. 

nitrous,  276. 

ozonic,  70. 

petroleum,  204. 

phenyl,  360. 

propargylethyl,  333. 

sulphuric,  268,  277. 
Ethers,  267. 

compound,  267,  275. 

haloid,   205. 

mixed,    267. 

phenyl,  360. 

simple,  209,  267. 
Ethidene  chloride,  328. 

compounds,  328. 

hydroxamine,   319. 

hydroxylamine,  296. 
Ethine,   329. 
Ethol,  279. 
Ethyl  acetate,  278. 

acetoacetate,  278. 

benzene,  342. 

borate,  124. 

bromide,  208. 

carbinol,  219. 

chloride,  208. 

dimethylcarbinol,  221. 

hydroxide,  214. 

iodide,  208. 

malonate,  279. 

mercaptan,   285. 

methylcarbinol,  220. 

morphine,  434. 

nitrate,  276. 

nitrite,  276. 

oxide,  268. 

pyridines,  398. 

strychnium  iodide,  432. 

sulphate,  277. 

sulphydrate,  285. 

urethane,  313. 
Ethylene,  327. 

alcohol,  222. 

chlorhydrine,  279. 

chloride,  280,  328. 

compounds,  328. 

diamine,  299. 

ethenyl  amidene,  299. 

glycol,  222. 

hydroxide,  222. 

oxide,  269. 

Ethylidene   compounds,   328. 
Eucalypteol,   383. 
Eucalyptol,  383. 
Euphorine,  314. 


464 


INDEX 


Evaporation,  15. 
Exalgine,  372. 

Fahrenheit's  scale,  12. 
Farad,  21. 
Fats,  282. 

phosphorized,  282. 
Fatty  compounds,  199,  201. 
Feldspar,  178,   180. 
Fermentation,  215. 

acetic,  215,  252. 

butyric,  216,  253. 

lactic,  216,  262. 

test,  249. 
Ferments,  false,  216. 

true,  215. 
Ferric  acetates,  136. 

chloride,   135. 

citrate,  136. 

ferrocyanide,  136. 

hydroxide,    134. 

with  magnesium  oxide,  115. 

oxide,  134. 

phosphate,  136. 

sulphates,  135. 

sulphide,  135. 
Ferroso-ferric  oxide,  134. 
Ferrous  acetate,  136. 

bicarbonate,  136. 

carbonate,  136. 

chloride,   135. 

ferricyanide,   137. 

hydroxide,   134. 

oxide,  134. 
.     phosphates,    136. 

sulphate,  135. 

sulphide,   134. 
Ferrum  reductum,  133. 
Filtration,  67. 
Fire-damp,  203. 
Flavaniline,  372. 
Flowers,    17. 
Fluorene,  385. 
Fluoresceine,  349,  350. 
Fluorine,  73. 
Fluor  spar,  73. 
Flux,  black,  160. 
Force,  1. 

chemical,  48. 

electromotive,  2Q. 
Formal,  233. 
Formaldehyde,  228. 
Formaline,  228. 
Formals,  232. 
Formamide,  312. 
Formin,  311). 
Kormunifrile,  303,  305. 
Formose,  229,  240. 
Formula^,  32. 

algebraic,    1113. 

empirical,    :{-J. 

general,    !!>:!. 

graphic,  47,  193. 


Formulae,  rational,  46. 

typical,  47. 
Fossil  resins,  385. 

wax,  204. 

Fowler's  solution,   115. 
Freezing  point,  11,  15. 
Fructose,  241. 
Fruit  sugar,  241. 
Fucose,  237. 
Function,  36. 
Furazoles,  393. 
Furfural,  392. 
Furfuraldehyde,  392. 
Furfurane,  392. 
Furfurole,  392. 

reaction,   247. 
Furole,  392. 
Fusel  oil,  220. 
Fusing  point,   14. 
Fusion,  13. 

latent  heat  of,  14. 

Gadinin,  282. 
Galactose,  241. 
Galena,   138,   140. 
Gallisin,  240,  244. 
Gallium,  177. 
Galvanic  battery,  19. 

cell,  19. 

circuit,  19. 

electricity,  18. 
Garnet,   178. 
Gas,  carbonic  acid,  272. 

laughing,  97. 

tar,  341. 
Gases,  4,  10,  15. 

absorption  of,  11. 
Gasoline,  204. 
Gelatin,  explosive,  247. 

sugar,  323. 

Geneva  convention,   199. 
Germicides,  444. 
Glass  of  antimony,   122. 

soluble,  153. 

water,  153. 
Glauber's  salt,   153. 
Glonoin,  280. 
Glucinium,  177. 
Glucosazone,  381. 
Glucose,   240. 
Glucoses,  237. 
Glucosides,  361. 
Glucosyl  phenate,  361. 
Glucovanillin,  362. 
Glycorides,  280. 
(Jly.-erine,   223. 
Glycerites,  224. 
Glycerol,  223. 

eaters  of  organic  acids,  281, 

halohydrines,  280. 

ketone,  237. 

tri nitrate,  280. 
Uv.vrols,   222,   224. 


INDEX 


465 


Glycine,   323. 
Glycogen,  245. 
Glycocoll,   323. 

trimethyl,  298. 
Glycocolls,  322. 
Glycol  ethene,  222. 

ethylene,  222. 

halohydrines,  279. 

monothioethylene,  286. 

tetramethylethylene,   222. 
Glycols,  221. 

xylylene,  352. 
Glycolyl  aldehyde,  237. 

urea,  395. 
Glyoxal,  233,  262. 
Glyoxaline,  396. 
Glyoxyldiureide,  395. 
Gold,  129. 

fulminating,   308. 

trichloride,  129. 
Goulard's  extract,   141.' 
Gram,  calorie,  12. 

equivalent,  31,  37. 

molecule,  29. 
Granulose,  245. 
Grape  sugar,  240. 
Graphite,    125. 
Gravity,  specific,  3. 
Grignard's  compounds,  290. 

reactions,  290. 
Groups,  characterizing,  198. 
Guaiacol,  347,  349. 
Guanidine,  301. 
Guanidines,  substituted,  301. 
Guanides,  405. 
Guanine,  411. 
Guaranine,  411. 
Gum  resins,  385. 
Gums,  246. 
Gun   cotton,   247. 

powder,  158. 
Guvacine,  422. 
Gypsum,  169. 

Halide  anhydrides,  270. 
Halides,  acidyl,  270. 
Halogens,  73. 
Hausmannite,    131. 
Heat,   11. 

changes  in  volume  caused  by,  12. 

effects  of,  11. 

latent,  14. 
of  fusion,  14. 
of  vapor,  16. 

measure  of,  12. 

quantity  of,   11. 

specific,   17. 

units  of,  62. 
Heavy  spar,  172. 
Helium,  72. 
Hematin,  273. 
Hematite,  132. 
Hematoporphyrin,  273. 


Hemiterpenes,  382. 

Hemochromogen,  273. 

Hemoglobin,  273. 

Heptoses,  236. 

Heroine,  434. 

Heterocyclic  compounds,  200,  334,  389, 

414. 

Heteroxanthine,  410. 
Hexacarbocyclic  compounds,  336. 
Hexadiene,  335. 
Hexads,  30,  31. 
Hexahydrobenzene,  335,  381. 
Hexahydrocymene,  382. 
Hexahydropyrazine,  400. 
Hexahydropyridine,  398. 
Hexamethylene,  335. 

tetramine,  319. 
Hexatriene,  335. 
Hexene,  335. 
Hexites,  225. 
Hexoses,  236,  237. 
Histidin,  396. 
Homatropine,  427. 
Homologous  series,  193. 
Horn  lead,  138. 
Hydantoin,  317,  395. 
Hydracetine,  381. 
Hydracids,  36. 
Hydramines,  296,  319. 
Hydrargyrum,  184. 
Hydrates,  64. 
Hydrazidos,  302,  303. 
Hydrazine,  96. 

compounds,  379. 
Hydrazines,  302,  379. 

aromatic,  379. 
Hydrazobenzene,  378,  379. 
Hydrazo  compounds,  378. 

nitrogen,  293. 
Hydrazones,  377. 

aldehyde,  321. 

ketone,  321. 
Hydrion,  35. 

Hydroaromatic  compounds,  381. 
Hydrocarbons,  194,  201,  202. 

acetylene  series,  201,  329. 

aliphatic,  201. 

condensed,  386. 

diacetylene,    201. 

diolefine,  330. 

ethene  series,  327. 

hydroaromatic,  381. 

methane  series,  201. 

monobenzenic,  341. 

olefine  series,  327. 

saturated,  201. 
Hydrocotarnine,  436,  438. 
Hydrogen,  57. 

antimonide,   121. 

arsenide,  111,  115. 

bromide,  80. 

chloride,   76. 

cyanide,  303. 


466 


INDEX 


Hydrogen,  dioxide,  69. 

fluoride,  73. 

iodide,  82. 

nitride,  95. 

peroxide,    69. 

phosphides,  106. 

sulphide,  85. 

sulphuretted,  85. 
Hydrolysis,  33,  (.4. 
Hydroimphthulenes,    386. 
Hydropyridines,  398. 
Hydropyrimidines,  398. 
Hydropyrroles,  393. 
Hydroquinone,  349. 
Hydrosulphides,  87. 
Hydroterpenes,  382. 
Hydrouracil,  401. 
Hydroxamines,  296,  319. 
Hydroxidion,   35. 
Hydroxides,  37,  64. 

alkyl,  211. 

basic,  64. 

hydrocarbon,  210. 
Hydroxyl,  37. 

determination   of,   284. 
Hydroxylamine,  97. 

compounds,  292. 
aromatic,   370. 
Hyoscine,  427. 
Hyoscyamine,  426. 
Hypnone,  355. 
Hypophosphites,  108. 
Hypoxanthine,  411. 

Iceland  spar,   170. 
Ichthyol,  287. 
Imide  nitrogen,  293. 
Imido  group,  293. 
Imidoparaffins,  293. 
Imides,  310,  313,  318. 
Imine  bases,  292. 
Imine  nitrogen,  293. 
Imines,  296,  313. 
Imino  group,  293. 
Impenetrability,  2. 
Indene,  385. 
Indestructibility,  2. 
Indican,    363. 

urinary,  417. 
Indicanin,  363. 
Tmliglucin,   363. 
Indigo  blue,  417. 

white,  418. 
Indigotine,  417. 
Indium,  177. 
Indole,  415. 

homologues,   415. 
Indoxyl,  41  (i. 
Induline  dyes,  379. 
Indulinr,   241,   2  Hi. 
lii'-i-lia,  2. 
I  in. site,    :W2. 
Insulators,  17. 


Inulin,  241,  246. 
Inversion,  241. 
Invert  in,   361. 
lodidion,  83. 
Iodides,  82. 
Iodine,   81. 

chlorides  of,  83. 

number,  HiibPs,  332. 

oxyacids  of,  82. 
lodoform,  207. 
lodophenols,   348. 
lodoquinine  sulphate,  429. 
lonization,  35. 
Ions,  17,  35. 
Iridium,   147. 
Iron,   132. 

acetates  of,  136. 

chlorides  of,  135. 

citrates  of,  136. 

dialysed,  134. 

galvanized,    133. 

group,  130. 

hydroxides  of,  134. 

magnetic  oxide  of,   134. 

oxides  of,  134. 

phosphates  of,   136. 

reduced,   133. 

spathic,  136. 

sulphates  of,   135. 

sulphides  of,  134. 
Ironstone,    132. 
Isatine,   417. 
Isoacetonitrile,  306. 
Isobenzonitrile,  306,  373. 
Isocholine,  296. 
Iso  compounds,  202. 
Isocyanates,  307. 
Isocyanides,  295,  306. 
Isodipyridine,  424. 
Isodulcite,  237. 
Isoindole,   416. 
Isoleucine,  325. 
Isomaltose,  240,  244. 
Isomeres,  optical,  239. 
Isomerism,  194,  337. 

place,  260,  337. 

position,   260. 

space,  238. 

stereo,  238. 
Isomorphism,  s. 
Isonitriles,  295. 
Isopropyl  carbinol,  220. 
Isoquinoline,  419. 

alkaloids,  421,  433. 
Ivory  black,  126. 

Jaborandine,  428. 
Jaborine,  428. 
Japaconine,  440. 
-Japaronit  inr,    440. 
•  lavellc   \vatrr,   158. 
Jervine,  441. 


INDEX 


467 


Kaolin,    180. 
Kathod^,  19. 
Rations,  20,  35,  45. 
Kelp,  81. 

Kerrttes  mineral,  122. 
Kerosene,  204. 
Ketohydrazones,  380. 
Ketone  acids,  266. 

dimethyl,  234. 

glycerol,  237. 

hydrazones,   321. 

phenylmethyl,  355. 
Ketones,  225,  233. 

aromatic,  354. 

hydroaromatic,  383. 
Ketopiperazines,  323. 
Ketopurines,  411. 
Ketoses,  236. 
Ketoximes,  320. 
Kilowatt,  41. 
King's  yellow,  114. 
Knock-out-drops,  232. 
Krypton,  72. 

Labarraque's  solution,  154. 

Labile  substances,  49. 

Labradorite,  180. 

Lacmoid,  349. 

Lactam,  methyl guanidinacetic,  302. 

Lactams,  323. 

Lactides,  261,  283. 

Lactones,  261,  283. 

Lactose,   244. 

Lampblack,   126. 

Lapis  infernalis,   165. 

Laughing  gas,  97. 

Law  or  laws,  Boyle-Mariotte,  10. 

Dalton-Gay  Lussac,  13. 

of  Ampere,  24. 

of  Avogadro,  24. 

of  Charles,  13. 

of  definite  proportions,  22. 

of  Gay-Lussac,  24. 

of  Graham,  58. 

of  Henry,  11. 

of  multiple  proportions,  23. 

of  reciprocal  proportions,  23. 

Ohm's,  20. 

periodic,  54,  55. 
Lead,  138. 

acetates,  140. 

black,  125. 

carbonate,  141. 

chamber  crystals,  99. 

chloride,   140. 

chromate,  140. 

dioxide,   139. 

group,    138. 

iodide,  140. 

monoxide,  139. 

nitrates,   140. 

oleate,   139. 

oxides,  139. 


Lead,  oxychlorides,  140. 

red,   139. 

salts  of,   140. 

subacetate,  14L 

sugar  of,  140. 

sulphate,  140. 

sulphide,   140. 

white,   141. 
Leads,  electric,  19. 
Lecithins,  282. 
Lethol,   279. 
Leucine,  325. 
Leucines,  325. 
Leucomames,  442. 
Leucopararosaniline,  389. 
Levigation,    170. 
Levulose,  241. 
Lichenin,  246. 

Light,  chemical  effects  of,  51. 
Lignin,  247. 
Lime,  168. 

chlorinated,   169. 

chloride  of,  169. 

milk  of,  169. 

quick,  168. 

slaked,  169. 

water,  169. 
Limestone,   170. 
Linkages,    196. 
Liquefaction,    16. 
Liqueurs,   219. 
Liquids,  4,  14,  15. 

diffusion  of,  9. 
Liquor  ammonii  acetatis,  167. 

calcis,   169. 

chlori  compositus,  75. 

hydrogenii  dioxidi,  70. 

iodi  compositus,  82. 

plumbi  subacetatis,   141. 
Litharge,  139. 
Lithia  water,  150. 
Lithium,    149. 

bicarbonate,  150. 

bromide,   149. 

carbonate,  150. 

chloride,  149. 
Loadstone,    134. 
Loganiaceae,  alkaloids  of,  431. 
Lucifer  disease,  106. 
Lugol's  solution,  82. 
Lunar  caustic,  165. 
Lutidines,  398. 
Lysidine,  299. 
Lysol,  347. 

Maclaurine,  360. 
Magma  bismuthi,  143. 
Magnesia,  173. 

mixture,  109. 
Magnesite,   174. 
Magnesium,  173. 

carbonate,  174. 

chloride,   173. 

group,  172. 


468 


INDEX 


Magnesium,  hydroxide,  173. 

organic  compounds,  289. 

oxide,  173. 

phosphates,  174. 

pyrophosphate,  174. 

sulphate,  173. 
Magnetic   oxide,    134. 
Malachite,   181. 
Malonyldimethylurea,  404. 
Malonylguanide,  405. 
Malonylurea,  404. 

group,  403. 
Malt,  214. 
Maltose,  244. 
Manganates,  132. 
Manganese,  131. 

oxides,   131. 

salts,  132. 
Manganite,  131. 
Mannitan.  225. 
Mannite,  225. 
Mannitol,  225. 
Mannose,  240. 
Marble,  170. 
Marsh  gas,  203. 
Martius'  yellow,  387. 
Mass,  action,  51. 
Massicot,   130. 
Matter,   1. 

general  properties  of,  2. 

states  of,  4. 
Meconine,  436. 
Meerschaum,   173. 
Megohm,  21. 
Melampyrite,  225. 
Melecitose,  245. 
Melitose,  245. 
Membranes,  permeable,  9. 

semipermeable,  10. 
Menthan,  383. 
Menthol,  383. 
Mercaptals,  286. 
Mercaptans,  285. 
Mercaptides,  285. 
Mercurammonium  chloride,  188. 
Mercurdiammonium  chloride,  188. 
Mercuric  chloride,  187. 

cyanide,  188. 

fulminate,  308. 

iodide,    188. 

nitrate,   189. 

oxide,   185. 

sulphate,  189. 
Mereurous    chloride,    186. 

iodide,  188. 

nitrate,  189. 

nxiili'.  185. 

sulphate,  189. 
Mercury.    I  si. 

aimnonialrd.   188. 

chlorides.    Is*''- 

formaniide,  312. 

fulminating,   308. 


Mercury,  iodides,  188. 

nitrates,   189. 

oxides,  185. 

phenate,  346. 

sulphates,  189. 
Meroquinene,    431. 
Mesitylene,  342. 

glycerol,  352. 
Meso  compounds,  202. 
Mcsnxalyhirea,   266,  405. 
Metachloral,  231. 
Meta  compounds,  338,  339. 
Metudiazine,   309. 
Metadioxybenzene,  349. 
Metaldehyde,  230. 
Metallocyanidea,  309. 
Metalloids,  51. 
Metals,  51,  53. 

noble,   102. 
Metamerism,   194. 
Metathesis,  33. 
Methanal,  228. 
Methane,  203. 

series,  201. 

triphenyl,   389. 
Methemoglobin,  273. 
Methene  chloride,  206. 
Methenyl,  chloride,  206. 

iodide,  207. 
Method,  see  Test. 
Methol,  279. 

Methoxyben/aldehyde,  354. 
Methoxyparaoxybenzaldehyde,  354. 
Methyl,   amine.'  295. 

acetanilide,  372. 

benzene,   342. 

bromide,  207. 

carbinol,  214. 

carbylamine,  306. 

chloride,  205. 

coniine,  422. 

cyanide,  306,  313. 

ethyl   oxide,  267. 

glycocollj  323,  324. 

guanidine,   301. 

hydride,  203. 

hydroxide,  214. 

indoles,    415,   416. 

iodide,  207. 

isocyanide,  306. 

ieopropylcarbinol,  221. 

morphine,  434,  438. 

morphine  methine,  438. 

oxalate,   387. 

oxide,    267. 

phenylhydrazine,  380. 

piperidine.   398. 

propylcarhinol.   221. 

pyridines,  398. 

quinine.  430. 

slryclmium   iodide,  432. 

uraeils,    402. 

uramine,  301. 


INDEX 


469 


Methyl,  xanthines,  410. 

Methylal,  233. 

Methylene,  chloride,  206. 

Meunier's  compounds,  291,  371. 

Mica,   173,   178,   180. 

Microhm,  21. 

Milliampere,  21. 

Mineral  green,  183. 

Minderus,  spirit  of,  167. 

Minium,   139. 

Mitis  green,  183. 

Mixture,  22. 

Mixtures,  isomorphous,  23. 
of  solids,  23. 

Mol,  29. 

Molasses,  242. 

Molecule,  24,  25. 

Molecular  theory,  24. 
volume,  29. 
weight,   26. 

determination  of,  195. 

Molybdenum,  128. 

Monacetin,  223,  280. 
Monads,  30,  31. 
Monamides,  310. 
primary,   311. 
secondary,  311. 
tertiary,  311. 
Monamines,  292. 
primary,  292. 
secondary,  294. 
tertiary,  295. 
Monobenzenic  compounds,  341. 

paraquinones,  351. 
Monobromocamphor,  384. 
Monochlormethyl  chloride,  206. 
Monoethylic  sulphate,  277. 
Monoglycerides,  223,  280. 
Monoketones,  233,  354. 
Monomorphyl  sulphate,  434. 
Mononitroparaffins,  292. 
Monophenyl  sulphate,  366. 
Monosaccharides,  236. 
Monoses,  236. 

Monothioethylene  glycol,  286. 
Monsel's  salt,  136. 
Monurei'des,  316. 
Morphine,  434,  438. 
Morphium,  420. 
Morrhuine,  282. 
Mucilages,  246. 
Murexide,  404. 
Muscarin,  297. 
Must,  218. 

Mustard  oils,  308,  333,  363. 
Myazine  compounds,  400. 
Mydaleme,  300. 
Myrosin,  333,  361. 

Naphtha,   204. 
Naphthalene,  386. 
Naphthenes,  381. 
Naphthol  yellow,  387. 


Naphthols,  386. 

substituted,  387. 
Naphthoquinones,  387. 
Narceine,  436,  438. 
Narcotine,  436,  438. 
Nascent  state,  59. 
Negative  plate,  19. 

pole,   19. 
Neon,  72. 
Neuridine,  300. 
Neurine,  297. 
Neutral   reaction,  33. 
Nickel,  180. 

group,  180. 

sulphate,  180. 
Nicotine,   423. 
Niobium,  128. 
Niton,  72. 
Nitrates,  102. 
Nitre,  157. 
Nitrile  bases,  292. 
Nitriles,  303,  305. 

acid,  305. 

of  carbonic  acids,  307. 

of  thiocarbonic  acids,  307. 
Nitrites,   101. 
Nitro,  292. 

acids,  321,  370. 

alcohols,  319. 

aldehydes,  319. 

anisols,  369. 

benzenes,  367. 

benzol,  367. 

cellulose,  247. 

cresols,  370. 
Nitrogen,  94. 

acids  of,  100. 

amide,  293. 

amino,  293. 

azo,  293. 

bromide,  97. 

chloride,  97. 

diazo,  293. 

dioxide,  98. 

group,  93. 

halides,  97. 

hydrazo,  293. 

imide,  293. 

imino,  293. 

iodide,  97. 

monoxide,  97. 

nitrile,  293. 

oxides  of,  97. 

pentoxide,   100. 

peroxide,  99. 

tetroxide,  99. 

trioxide,  99. 
Nitroglycerin,  280. 
Nitroketones,  319. 
Nitroparaffins,  292. 
Nitrophenetols,  369. 
Nitrophenols,  369. 
Nitrosonaphthols,  387. 


470 


INDEX 


Nitrosophenols,  370. 
Nitrosyl  bichloride,  102. 

chloride,  102. 
Nitrotoluenes,  368. 
Nomenclature,  42. 

of  alcohols,  211,  221. 

of  alkaloids,  420. 

of  amines,  293. 

of  carbon  compounds,  198. 
Non-metals,  52. 
Nonoses,  236. 

Nordhausen  oil  of  vitriol,  93. 
Normal  compounds,  202. 

conditions,  4. 
Nortropan,  424. 
Nuclein  bases,  409. 
Nucleus,  200. 

benzene,  334. 

Obtained  substances,  208. 

Occlusion,  58. 

Octoses,  236. 

Ohm,  21. 

Oil,  bone,  397. 

cod-liver,  282. 

fusel,  220. 

mustard,  333. 

of  bitter  almonds,  353. 

of  Dippel,  397. 

of  vitriol,  90. 

sperm,   282. 
Oils,  drying,  282. 

fixed,  282. 

greasy,  282. 

lubricating,  204. 

mustard,  308. 

neutral,  282. 

non-drying,  282. 

semi-drying,  282. 
Ol,  211. 

Olefiant  gas,  327,  328. 
Olefine,  327. 

acetylene  series,  201. 

series,  201,  327. 

terpenes,  382. 
Olefines,   201. 
Oleoresins,  385. 

Open  chain  compounds,  199,  201. 
Opium  alkaloids,  434,  437. 
Optical  activity,  238. 

isomeres,  239. 

Organic  compounds,  191,  192. 
Organo-halide  compounds,  289. 
Organo-magnesium    compounds,  289. 
Organo-metallic  compounds,  288. 
Orientation,  337. 
Orpiment,  114. 
Ortho  acids,  108. 

compounds,  338,  339. 

diazine,  399. 

dioxybenzene,  349. 

quinones,  350. 
Osazones,  236,  249,  380. 


Ose,  236. 
Osmium,   128. 
Osmosis,  9. 
Osmotic  equivalent,  9. 
Otoliths,  170. 
Oxalylurea,  395. 
Oxazine,  399. 
Oxethylamine,  319. 
Oxhydryl,  37. 
Oxidation,  60. 
Oxides,  61. 

basic,  61. 

indifferent,  61. 

neutral,  61. 

saline,  61. 
Oxime  group,  301. 
Oxindole,  374,  417. 
Oxonium  compounds,  289. 
Oxyacids,  36,  259. 
Oxyuldehydes,  228. 
Oxyamides,   322. 
Oxyamines,  296,  298,  319. 
Oxybenzaldehyde,  354. 
Oxycholine,  298. 
Oxycinchonine,  430. 
Oxycyanides,  228. 
Oxydimorphine,  434. 
Oxygen,  59. 
Oxygenium,  59,  60. 
Oxy hemoglobin,  273. 
Oxyhydrocymene,  383. 
Oxyindole,  416. 
Oxymorphine,  434. 
Oxynaphthalenes,  386. 
Oxyneurine,  298. 
Oxyphenylalanine,  374. 
Oxyphenylethylamine,   375. 
Oxypurines,  411. 
Oxysalts,  38. 
Ozocerite,  204. 
Ozone,   61. 
Ozonic  ether,  70. 

Painter's  colic,  141. 
Palladium,  147. 
Papaveraldine,  437. 
Papaverine,  436,  437. 
Para  acetophenetidine,  373. 
Para  compounds,  338,  339. 

coniine,  423. 

dioxybenzene,  349. 
Paraffin,  204. 

series,  201. 
Paraffins,  202. 

amido,  292. 

haloid  derivatives  of,  204. 

imido,  293. 

monohalogen,  205. 

nitro,  292. 

nitrogen  derivatives  of,  291. 

oxidation  products  of,  208. 

sulphur  derivatives  of,  285. 
Para  formaldehyde,  228. 


INDEX 


471 


Paraldehyde,  230. 
Paramorphine,  436. 
Paramylum,  246. 
Para  quinones,  351. 

triazine,  414. 

xan thine,  410. 
Parchment  paper,  247. 
Paris  green,  115,  183. 

yellow,   140. 
Pearl  ash,  159,  160. 
Pentads,  30,  31. 
Pentamethylenediamine,  299. 
Pentene,  330. 
Pentites,   225. 
Pentoses,  236,  237. 
Pentosides,  361. 
Periodic  law,  54,  55. 
Perissads,  30. 
Permanganates,  132. 
Petrolatum,   204. 
Petroleum,  204. 

ether,  204. 
Phenacetine,   373. 
Phenanthrene,  385. 

alkaloids,  422,  433. 
Phenates,  346. 
Phenetidines,  369,  373. 
Phenetol,  361. 
Phenol,  345. 

cymylic,  347. 

dyes,  350. 

esters,  347. 

methylisopropyl,  347,  348. 

phthalem,  350. 

sulphonates,  366. 

synthetic,  345. 
Phenols,  344,  386. 

benzylic,  347. 

cresylic,  347. 

dihydric,  348. 

dimethyl,  347. 

diphenyl,  389. 

ethyl,  347. 

monohydric,  344. 

substituted,  348. 

trihydric,  350. 
Phenones,  354. 
Phenyl,  343. 

acetamide,  372. 

alanine,  374. 

amines,  371,  373. 

benzenes,  388. 

carbylamine,  373. 

dimethylpyrazolon,  394. 
Phenylene,   343. 

diamines,  373,  380. 
Phenyl  glucosides,  361. 

glycocoll,  375. 

guanidine,  375. 

hydrazine,  379,  380,  381. 
test,  249. 

hydrazones,  380. 

hydroxide,  345. 


Phenyl  hydroxylamine,  370. 

isocyanide,  306. 

salicylate,  358. 

sulphide,  365. 

uracil,  402. 

urethanes,  314,  375. 
Phloretin,  364. 
Phloridzin,  364. 
Phloroglucin,  350,  364. 
Phlorose,  364. 
Phosgene,  271. 
Phosphates,  109. 
Phosphine,  106. 
Phosphines,  326. 
Phosphorus,  103. 

acids  of,  107. 

halides,   107. 

organic  compounds  of,  326. 

oxides,   107. 

oxychloride,  107. 

pentachloride,  107. 

pentoxide,  107. 

trichloride,   107. 

trioxide,  107. 
Phthalamide,  373. 
Phthaleins,  350. 
Phthalimide,  373. 
Physical  change,  1. 
Physostigmine,  441. 
Picolines,  398. 
Pilocarpene,  428. 
Pilocarpidine,  428. 
Pilocarpine,   428. 
Pinacone,  222. 
Piperazine,  400. 
Piperidei'nes,  398. 
Piperidine,  398,  423. 

alkaloids,  421,  422. 
Piperidines,  398. 
Piperine,  423. 
Plaster  of  Paris,  170. 
Platinic  chloride,  148. 
Platinum,  147. 

black,  147. 

group,  147. 

spongy,  147. 

tetrachloride,  148. 
Plumbago,  125. 
Plumbates,  140. 
Plumbites,   139. 
Pceonin,  350. 

Poisons,  78,  and  see  Toxicology. 
Poles,  electric,   19. 
Polymerism,   194. 
Polymerization,   229. 
Polymethylenes,  335. 
Polysaccharides,  236,  245. 
Ponceau  dyes,  387. 
Populin,  364. 
Porcelain,  218. 
Porter,  218. 
Positive  plate,  19. 

pole,  19. 


472 


INDEX 


Postulate,  see  Law. 
Potash,  156,  157,  160. 
Potassa,  156. 
Potassium,  156. 

acetate,  159. 

alcoholate,  217. 

alum,  179. 

arsenite,   115. 

bromate,  157. 

bromide,    157. 

carbonates,  159. 

chlorate,  158. 

chloride,  157. 

cyanates,  307. 

cyanide,  162. 

dichromate,   159. 

ethylate,  217. 

ferricyanide,  163. 

ferrocyanide,  162. 

hypochlorite,  158. 

hydrate,  156. 

hydroxide,  156. 

iodide,  157. 

myronate,  333. 

nitrate,  157. 

oxalates,   160. 

oxides,    156. 

permanganate,  159. 

phenate,  346. 

pyrosulphate,  159. 

sulphates,  158. 

sulphites,    159. 

tartrates,  160. 
Powder  of  Algaroth,  121. 

putty,  146. 

smokeless,  247. 
Precipitation,  67. 
Pressure,  4. 

critical,  15,  16. 
Preston  salts,  167. 
Process  (see  also  Reaction,  Reagent, 

Test). 

ammonia,  155. 

Leblanc's  155. 

Solvay,  155. 
Proline,  393. 
Propanon,  234. 
Propantriol,  223. 
Propine,  330. 
Propyl  carbinol,  220. 

hydroxide,   219. 

piperidine,  398,  422. 
Propylene,  330. 
Proteinochrome,  416. 
Proteinochromogen,  416. 
Prussian  blue,   136,  163. 
Pseudo  aconitine,  440. 

conhydrine,  422. 

morphine,  434. 
Ptomaines,  442. 
Purine,  406. 

bases,  409. 

compounds,   400. 


Purine  group,  400,  405. 
Purpurin,  388. 
Putrefaction,  443. 
Putrescin,  299. 
Putty  powder,  146. 
Pyrazine,  399. 
Pyrazolons,  394,  395. 
Pyridiazine,  399. 
Pyridine,  397. 

alkaloids,  421. 

bases,   397. 

homologues,   398. 

methylpyrrole,  424. 
Pyrimidine,  399. 

derivatives,  400. 
Pyrites,  84,  110,  132,  134. 

copper,   181. 
Pyrocatechin,  349. 
Pyrocatechol,  349. 
Pyrocomane,  398. 
Pyrodine,  381. 
Pyrogallol,  350. 
Pyrolusite,    131. 
Pyrone,  397. 
Pyroxam,  245. 
Pyroxylic  spirit,  252. 
Pyroxylin,  247. 

soluble,   247. 
Pyrrazoles,  393. 
Pyrrole,  392,  424. 
Pyrrolidine,   393. 

alkaloids,  421. 

piperidine  alkaloids,  421,  424. 

pyridine  alkaloids,  421,  423. 
Pyrroline,  393. 
Pyrromonazoles,  393. 

Quaternary  ammonium  compounds,  295, 
296,  297,  298. 

hydroxides,   293. 
Quercite,  382. 
Quicklime,  168. 
Quicksilver,   185. 
Quina  red,  360. 
Quinicino,  430. 
Quinidine,  430. 
Quinine,  429. 

hydrosulphate,  429. 

sulphate,  429. 
Quinol,  349. 
Quinoline,  419. 

alkaloids,  421,  428,  429. 

compounds,  418. 
Quinone,  351. 
Quinones,  350,  386,  387. 
Quinoxime,  370. 

Radicals,  45,  192. 

of  acids,  46. 
Raffinose,  245. 
Reaction,    32     (see    Process,    Reagent, 

Test). 
Reactions,  33. 


INDEX 


473 


Reagent,  Frohde's,  435. 

Marquis',  436. 

Nessler's,  96. 

Schiff's,  315. 
Realgar,  114. 
Reaumur's  scale,  12. 
Rectified   spirit,   217. 
Reduction,  58. 
Refractory  substances,  13. 
Residues,  46. 
Resins,  384. 
Resistance,  20. 
Resorcin,  349. 
Resorcinol,  349. 

phthalei'n,  350. 
Reversible  reactions,  50. 
Rhamnose,  237. 
Rhigolene,  204. 
Rhodium,  147. 
Ribose,  237. 
Rings,  200. 
Roburite,  368. 
Rochelle  salt,  162. 
Rock  crystal,  127. 
Rosin,  382. 
Rubidium,  163. 
Ruby,   178,   181. 
Ruthenium,  147. 

Sabadilline,  441. 
Saccharates,  238,  241,  243. 
Saccharin,  366. 
Saccharobioses,   236,  241. 
Saccharose,  242. 
Saccharotrioses,   236. 
Saccharum  lactis,  244. 
Sal  ammoniac,  166. 
Salacetol,  358. 
Salseratus,    160. 
Salicin,  364. 
Salicyl  hydride,  354. 
Salicylal,  354. 
Salicylide,  364. 
Saligenin,   352. 
Salipyrine,  394. 
Salol,   358. 
Sal  soda  155. 
Salt,    152. 

of  lemon,  160. 

of  Saturn,  140. 

of  sorrel,  160. 

of  tartar,  159,  160. 

rock,  152. 

sea,  152. 

soda,  155. 

table,  152. 
Saltpeter,   157. 

Chile,  152. 

cubic,  152. 
Salts,  36,  38,  39. 

acid,  38,  45. 

basic,  38,  45. 

double,  45. 


Salts,  haloid,  38. 

modified,  397. 

neutral,   45. 

normal,  45. 
Sal  volatile,  167. 
Sanguinarine,  397. 
Santonin,  364. 
Saponification,  276. 
Sapphire,  178. 
Saprine,  300. 
Sarcosine,  324. 
Sarkine,  411. 

Saturated  compounds,  196,  201. 
Scandium,  177. 
Scheele's  green,  115,   183. 
Schweinfurth  green,  115,  183. 
Scopolamine,  427. 
Scopoline,  427. 
Seidlitz  salt,   173. 
Selenite,  169. 
Selenium,  93. 
Selenmonazole,  393. 
Series,  electrochemical,  34. 
Silex,  127. 
Silica,   127. 
Silicates,  127. 
Silicium,  127. 
Silicon,  127. 

carbide,   127. 

chloride,  127. 

dioxide,  127. 
Silver,  164. 

acetylide,  329. 

bromide,   165. 

chloride,  165. 

fulminate,  308. 

german,  180. 

iodide,   165. 

monoxide,  164. 

nitrate,  165. 

oxides,    164. 
Skatole,  416. 

Smokeless  powder,  247,  280, 
Soaps,  282. 
Soapstone,  173. 
Soda,  155. 

baking,  156,  161. 

blackball,  155. 

caustic,  155. 

crystals,   155. 

lye,   152. 

salt,   155. 

washing,  155. 

water,  272. 
Sodium,  151. 

acetate,  155. 

acetylide,  329. 

alcoholate,  217. 

arsenates,  154. 

arsenites,  115,  154. 

bicarbonate,  156. 

borate,  154. 

bromide,   152. 


474 


INDEX 


Sodium  carbonates,  155. 

chlorate,  154. 

chloride,  152. 

dioxide,   151. 

ethylate,   217. 

group,    149. 

hydroxide,  151. 

hypochlorite,  154. 

hyposulphite,  153. 

iodide,  152. 

metaphosphate,  154. 

monoxide,  151. 

nitrate,   152. 

nitroprusside,  310. 

oxides,  151. 

permanganate,  155. 

phosphates,    153. 

pyroborate,  154. 

pyrophosphate,   154. 

sesquicarbonate,  156. 

silicates,  153. 

sulphates,  152. 

sulphite,  153. 

sulphovinate,  277. 

thiosulphate,  153. 

tungstate,  128. 
Solanidin,  364. 
Solanin,  364. 
Solids,  4. 
Solute,  14. 
Solution — Solutions,  14. 

chemical,  14. 

concentration  of,  37. 

decinormal,  38. 

dilute  14,  15. 

equivalent  normal,  38. 

molecular  normal,  37. 

normal,  37. 

percentage,  37. 

physical,  14. 

physiological  salt,  152. 

salt,  152. 

saturated,  15. 

simple,    14. 

solid,  23. 

standard,  38. 

strength  of,  37. 

supersaturated,    15. 

unsaturated,   15. 
Solubilities,  table  of,  446,  447. 
Solubility,  14. 
Solvay  process,  155. 
Solvent,   14. 
Somnal,   314. 
Rorbinose,   241. 
Sorbite,  225. 
Sorbitol,  225. 
Space  isomerism,  238. 
Spasmotoxine,   443. 
Specific  heat,  17. 

volume,  4. 

weight,  3. 
Spermaceti,   279. 


Spirit,  methylated,  214. 

neutral,  219. 

potato,  220. 

proof,  218. 

pyroxylic,  214,  252. 

wood,  214. 
Spirits,  216,  219. 

of  Minderus,  167. 

of  wine,  214. 
Spiritus  rectificatus,  217. 
Stability,  48. 
Stable  substances,  49. 
Stannates,  146. 
Stannic  chloride,  146. 

oxide,  146. 
Stannous  chloride,  146. 

hydroxide,  146. 

oxide,  146. 
Starch,   245. 

animal,  245. 

cellulose,  245. 

hydrated,  245. 

paste,  245. 

soluble,  245. 
States  of  matter,  4. 
Steel,   133. 

Stereochemistry,  238. 
Stereoisomerism,  238. 
Stethol,  279. 
Stibine,  121. 
Stibines,  326. 
Stilbene,  389. 
Stoichiometry,  41. 
Storax,   352. 
Strontianite,  171. 
Strontium,   171. 
Strychnidene,  432. 
Strychnine,  431. 
Strychnos  alkaloids,  431. 
Styracol,  349. 
Sublimate,  corrosive,   187. 
Sublimation,   17. 
Subsidence,   68. 
Substance,  1. 
Substitution,  196. 
Succinyl  morphine,  434. 
Sucrates,  243. 
Sugar,  beet,  243. 

barley,  243. 

burnt,  243. 

candy,  243. 

cane,   242. 

diabetic,    240. 

fruit,  241. 

gelatin,  323. 

grape,    240. 

invert,  241,  243. 

liver,  240. 

maple,  243. 

milk,  244. 

muscovado,  242. 

of  lead,  140. 

raw,  242. 


INDEX 


475 


Sulphates,  92. 
Sulphethylates,  277. 
Sulphides,  87,  284. 
Sulphites,  89. 
Sulpho,  85. 
Sulphocarbolates,  366. 
Sulphonal,  287. 
Sulphonation,  365. 
Sulphones,  284,  286,  366. 

of  thioaldehydes,  286. 
Sulphosion,  89. 
Sulphurylchloride,  88. 
Sulphovinates,  277. 
Sulphoxides,  284,  286. 
Sulphur,  84. 

aromatic  derivatives  of,  365. 

dioxide,  87. 

flowers  of,  84. 

group,  83. 

milk  of,  84. 

oxides,  87. 

oxyacids  of,  89. 

plastic,  84. 

precipitated,  84. 

roll,  84. 

sublimed,  84. 

trioxide,  88. 
Sultones,  387. 
Symbols,  31. 

Symmetrical  positions,  338. 
Synthesis,  33,  63. 

Talc,  173. 
Tannins,   360. 
Tantalum,  128. 
Tartar,  cream  of,  161. 

crude,  161. 

emetic,  162. 

salt  of,  159,  160. 

soluble,  160. 
Tartrates,  160. 
Tartronylurea,  404. 
Tellurium,  93. 
Temperature,   11. 

absolute,   13. 

critical,  15. 
Terpenes,  382. 
Terpin  hydrate,  383. 
Terpins,  383. 
Terra  alba,  170. 
Test   (Process,  Reaction). 

Almen,  249. 

Anderson,  397. 

bismuth  reduction,   249. 

biuret,  315,  318. 

Boettger,  249. 

copper  reduction,  248. 

Fehling,  248. 

fermentation,  249. 

Fischer,  249. 

furfurole,  247. 

Gallois,  383. 

Hoffman,  295,  375. 


Test,  Hofmeister,  326. 

Husemann,   436. 

indophenol,  372. 

Kjeldahl,  195. 

Kossel,   411. 

Marsh,    118. 

Mulder-Neubauer,  418. 

murexide,  408. 

Nessler,  96. 

Nylander,  249. 

osazone,  249. 

Pavy,  248. 

Pellagri,  435. 

phenylhydrazine,  249. 

pine-shaving,  346,  392,  393,  416. 

Piria,  375. 

pyrrole,  416. 

Eeinsch,    117. 

Riegler,  249. 

Scherer,  326,  375,  383. 

Tollens,  247. 

Trommer,  248. 

Wiedel,  402. 
Tetanine,  443. 
Tetanotoxine,  443. 
Tetrads,  30,  31. 
Tetra  hydrobenzenes,  335. 

hydrodiphenyl,  388, 

hydronaphthols,  387. 

hydropyridine  alkaloids,  421. 

hydropyridines,  398. 

hydropyrrole,  393. 

hydrostrychnine,  432. 

ketohexahydropyrimidine,  405. 

ketones,  235. 

methylammonium  hydroxide,  295. 

methylenediamine,  299. 

methylethylene  glycol,  222. 

methyleneimine,  393. 
Tetronal,  287. 
Tetroses,  236,  237. 
Thallium,   168. 
Thebaine,  436,  439. 
Thebaol,  439. 
Theine,  411. 
Theobromine,  410. 
Theophylline,  410. 
Theory,  atomic,  24. 

molecular,  24. 
Therm,  12. 
Thermal  capacity,  17. 

unit,  12. 

Thermometers,  11. 
Thiazine,  399. 
Thio,  85. 

acetals,  286. 

acids,  284,  287. 

alcohols,  284,  285. 

aldehydes,  284,  286. 

anhydrides,  87,  287. 

antimonates,  122. 

antimonites,    122. 

aromatic  compounds,  365. 


476 


INDEX 


Thio  azoles,  393. 

bases,  37. 
Thiocol,  349. 
Thio  ethers,  284,  285. 

ethylates,  285. 

glycols,  285. 

ketones,  284. 
Thiophene,  392. 
Thiophenol,  365. 
Thiourea,  316. 
Thymine,  402. 
Thymol,  347. 
Tin,  145, 

chlorides,   146. 

crystals,  146. 

foil,  146. 

group,  144. 

hydrates,  146. 

oxides,  146. 

plates,   146. 
Tinstone,   146. 
Tinctures,  216. 
Titanium,   144. 
Toluene,  342. 

sulphamide,  366. 

sulphonic  chlorides,  366. 
Toluidines,   372. 
Toluol,  342. 
Toluyl  benzene,  388. 
Toluylene,  389. 
Tolypyrine,   395. 
Topaz,  178. 
Toxalbumins,  443. 

Toxicology,   78,   116,  and  see  Poisons, 
Corrosives. 

aconite,  440. 

aldehyde,  230. 

ammonia,   167. 

aniline,  371. 

antimony,  123. 

arsenic,  115. 

atropine,  426. 

barium,  172. 

bismuth,  144. 

carbolic  acid,  346. 

carbon  dioxide,  274. 

carbon   disulphide,   288. 

carbon  monoxide,  271. 

chloral   hydrate,  232. 

chloroform,  207. 

copper,  184. 

cyanides,    304. 

digitalis,  363. 

hydrogen  sulphide,  86. 

illuminating  gas,  271. 

iodine,  82. 

lead,  141. 

mercury,  189. 

mineral  acids,  78. 

nicotine,  424. 

nitric  acid,  103. 

nitrobenzene,  368. 

nitrogen  Ictroxide,  100. 

opium,  439. 


Toxicology,  oxalic  acid,  258. 

phenol,  346. 

phosphorous,  105. 

potassium,    163. 

silver,  165. 

sodium,    163. 

strychnine,  433. 

sulphuric  acid,  92. 

zinc,  177. 
Toxines,  443. 
Transposition,  33. 
Transterpene,  383. 
Triacetin,  223,  280. 
Triacetonamine,    319. 
Triads,  30,  31. 
Triamides,    310. 
Triamines,   292. 
Triazines,  413. 
Tribrommethane,  207. 
Tributyrin,  281. 
Tricaprin,  281. 
Tricaproin,  281. 
Tricaprylin,  281. 
Trichlor  aldehyde,  230. 

methane,  206. 
Tricyanogen  chloride,  304. 
Tryglycerides,  223,  280. 
Triiodomethane,  207. 
Triketones,  235,  354. 
Triketohexahydropyrimidine,    404. 
Triketopurine,  406. 
Triketotetrahydroglyoxaline,    395. 
Trimargarin,  281. 
Trimethylamine,  295. 
Trimethylcarbinol,  220. 
Trimethylethylene,  330. 
Trimethylene  diamine,  299. 
Trimethyloxethylammonium  hydroxide, 

296. 

Trimethyloxethylideneammonium       hy- 
droxide, 296. 
Trimethylvinylammonium       hydroxide, 

297. 

Trimorphism,  8. 
Trinitroglycerol,  280. 
Trinitrophenols,  369. 
Triolein,  281. 
Triols,  223. 
Trional,  287. 
Trioses,  236,  237. 
Trioxyanthraquinone,  388. 
Trioxycyanidine,   307. 
Trioxymethylene,  228. 
Tripalmitin,  281. 
Triphenylbenzene,  388. 
Triphenylmethane,  389. 
Triple  phosphate,  174. 
Trisaccharides,  236,  245. 
Tristearin,  281. 
Tropan  alcohol,  425. 

alkaloids,  421,  424. 
Tropeines,  427. 
Troprolins,  387. 
Tropidine,  425. 


INDEX 


477 


Tropine,  398,  425. 

atropate,  427. 

tropate,  425. 
Tryptophane,  416. 
Tungsten,  128. 
TurnbulPs  blue,  137,  163. 
Turner's  yellow,  140. 
Turpentine,  382. 
Turpeth  mineral,  189. 
Tutty,    176. 
Tyrosine,  374. 

Unsaturatod  compounds,  197. 
Unsymmetrical  positions,  338. 
Uracil,  401. 

group,  400,  401. 
Uralium,  314. 
Uranium,  137. 
Uranyl,  138. 
Urates,  408. 

nitrate,  138. 
Urea,  314. 

nitrate,  315. 

oxalate,  315. 
Ureas,  compound,  316. 
Ureides,  316. 

diacidyl,  317. 

mixed,  317. 

monacidyl,  317. 
Urethanes,  313. 
Urotropin,  319. 
Uroxanthine,  417. 

Valence,   30. 
Valerene,  330. 
Vanadium,   128. 
Vanillin,  354. 
Vapor,  15,  16. 

latent  heat  of,  16. 
Vaporization,   15. 
Varech,  81. 
Vaseline,  204. 
Veratrine,  441. 
Veratrol,  349. 
Verdigris,  183. 
Veronal,  404. 
Verona  yellow,  140. 
Vichy  salt,  156. 
Vicinal  positions,  338. 
Vinegar,  252. 

wood,  252. 
Vitriol,  blue,  183. 

green,  135. 

oil  of,  90. 

white,  176. 
Volt,  21. 
Volume,  specific,  4. 

Water,    62. 

baryta,  172. 
chlorine,  75. 
in  the  body,  69. 
lime,   169. 
lithia,  150. 


Water,  maximum  density  of,  13. 

of  constitution,  64. 

of  crystallization,  8,  63,  64. 

oxygenated,  69. 

soda,  272. 
Waters,  bitter,  174. 

chlorides  in,  65. 

hardness  of,  66. 

impurities  in,  65. 

lead  in,  67. 

mineral,  68. 

natural,    64. 

nitrogen  in,  66,  67. 

organic  matters  in,  66. 

poisonous  metals  in,  67. 

potable,  64,  65. 

purification  of,  67,  68. 

solids  in,  65. 
Watt,  21. 
Wax,  204. 
Weight,  2. 

absolute,  3. 

apparent,  3. 

atomic,  26. 

equivalent,  31. 

molecular,  26,  195. 

relative,  3. 

specific,  3. 
White  lead,  138,  141. 

precipitate,  188. 
Wines,   218. 
Witherite,  172. 
Wort,  215. 

Xanthine,  410. 
bases,  409. 
Xanthone,  358. 
Xenols,  347. 
Xenon,  72. 
Xylenes,  342. 
Xylenols,  347. 
Xylidines,  372. 
Xylodin,  245. 
Xylols,  342. 
Xylose,  237. 
Xylyleneglycols,  352. 

Yeast,  215. 
Yellow  wash,  186. 

Zero,  absolute,  13. 
Zinc,  175. 

alkyls,  288. 

butter  of,  176. 

carbonate,  176. 

chloride,  176. 

ethide,  288. 

ethyl,  288. 

hydroxide,  176. 

methide,  288. 

methyl,  288. 

oxide,  176. 

sulphate,  176. 
Zirconia,  145. 
Zirconium,  145. 


ELEMENTS 


"o 

Atomi 

c  Weight 

"o 

Atomi 

c  Weight 

NAME 

I 

>, 

C/) 

Approx- 
itnate 

Interna- 
tional 
(1918) 
O=i6 

NAME 

a 

h 

in 

Approx- 
imate 

Interna- 
tional 
(19.8) 
O  =  i6 

Aluminium  
Antimony 

Al 

27 

27.1 

Molybdenum  
Neodymium    

Me 

Nd 

96 
144 

96.0 
144.3 

(Stibium) 

Sb 

120 

120.2 

Neon  

NP 

20 

202 

Argon 

A 

40 

39.88 

Nickel    

Ni 

58 

58  68 

Arsenic 

As 

75 

74.96 

Niton   (Radium 

Barium    .  . 

Ba 

137 

137.37 

Emanation  ) 

Nt, 

222 

222.4 

Bismuth  

Bi 

208 

208.00 

Nitrogen    . 

N 

14 

14.01 

Boron   

B 

11 

11.0 

Osmium   .  . 

OR 

191 

190.9 

Bromine    

Br 

80 

79.92 

Oxygen  .... 

O 

16 

16.00 

Cadmium  

Cd 

112 

112.40 

Palladium 

Pd 

107 

106.7 

Caesium    

Cs 

133 

132.81 

Phosphorus 

P 

31 

31.04 

Calcium   

Ca 

40 

40.07 

Platinum   . 

Pt 

195 

195.2 

Carbon  

C 

12 

12.005 

Potassium 

Cerium    

Ce 

140 

140.25 

(  Kalium  ) 

K 

39 

39.10 

Chlorine    

Cl 

35.5 

35.46 

Praseodymium  (  c  ) 

Pr 

141 

140.9 

Chromium  

Cr 

52 

52.0 

Radium    .  .  . 

Ra 

226 

226.0 

Cobalt    

On 

59 

58.97 

Rhodium    

Rh 

103 

102.9 

Columbium  (a)  .  . 

Cb 

93 

93.1 

Rubidium    

Rb 

85 

85.45 

Copper    (  Cuprum  ) 

Cu 

63 

63.57 

Ruthenium    

Ru 

102 

101.7 

Dysprosium    .... 

Dy 

162 

162.5 

Samarium   

Sa 

150 

150.4 

Erbium    

Er 

168 

167.7 

Scandium    

8c 

44 

44.1 

Europium 

Eu 

152 

1520 

Selenium 

Se 

79 

79.2 

Fluorine 

F 

19 

19  0 

Silicon   . 

Si 

28 

28.3 

Gadolinium    

Gd 

157 

157.3 

Silver  (Argentum) 

Ap 

108 

107.88 

Gallium   

Ga 

70 

69.9 

Sodium  (Natrium) 

Na 

23 

23.00 

Germanium 

Ge 

72 

725 

Strontium 

Sr 

87.5 

87.63 

Glucinum    (6) 

Gl 

9 

9  1 

Sulphur    

s 

32 

32.06 

Gold    (Aurum)    .  . 
Helium 

Au 
He 

197 
4 

197.2 
4  00 

Tantalum    
Tellurium    .  .  . 

Ta 
Te 

181 
127 

181.5 
127.5 

Holmium 

Ho 

163 

163  5 

Terbium    

Tb 

159 

159.2 

Hydrogen 

H 

1 

1  008 

Thallium    

T1 

204 

204.0 

Indium 

In 

115 

114  8 

Thorium    

Tli 

232 

232.4 

Iodine  .  . 

I 

127 

12692 

Thulium    

Tm 

168 

168.5 

Iridium 

Ir 

193 

193  1 

Tin  (Stannum)  .  .  « 

Sn 

118.5 

118.7 

Iron   (  Ferrum  ) 

Fe 

50 

55  84' 

Titanium  

Ti 

48 

48.1 

Krypton 

Kr 

83 

8292 

Tungsten 

Lanthanum 

La 

130 

139  0 

(  \Volframium  ) 

W 

184 

184.0 

Lead  (Plumbum) 

PI) 

207 

207  20 

Uranium    

TT 

238 

238.2 

Lithium 

Li 

7 

694 

Vanadium    

V 

51 

51.0 

Lutecium 

Lu 

17r> 

175  0 

Xenon 

Xe 

130 

130.2 

Magnesium 

Mg 

24 

24.32 

Ytterbium    (d)    .. 

Yh 

173 

173.5 

Manganese 

Mn 

55 

5493 

Yttrium 

Yt 

89 

88.7 

Mercury 

Zinc                

Zn 

65 

65.37 

(  Ui/drctrourum  } 

HP 

200 

2006 

Zirconium   

Zr 

90 

90.6 

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(6)   Also  formerly  known  as  Beryllium,   Be. 

(c)  Also  formerly  known  as  Didymium,  Di. 

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